Length of the smallest sub-string consisting of maximum distinct characters
Last Updated :
05 Aug, 2024
Given a string of length N, find the length of the smallest sub-string consisting of maximum distinct characters. Note : Our output can have same character.
Examples:
Input : "AABBBCBB"
Output : 5
Input : "AABBBCBBAC"
Output : 3
Explanation : Sub-string -> "BAC"
Input : "GEEKSGEEKSFOR"
Output : 8
Explanation : Sub-string -> "GEEKSFOR"
Method 1 (Brute Force)
We can consider all sub-strings one by one and check for each sub-string both conditions together
- sub-string's distinct characters is equal to maximum distinct characters
- sub-string's length should be minimum.
Implementation:
C++
/* C++ program to find the length of the smallest
substring consisting of maximum distinct characters */
#include <bits/stdc++.h>
using namespace std;
#define NO_OF_CHARS 256
// Find maximum distinct characters in any string
int max_distinct_char(string str, int n){
// Initialize all character's count with 0
int count[NO_OF_CHARS] = {0};
// Increase the count in array if a character
// is found
for (int i = 0; i < n; i++)
count[str[i]]++;
int max_distinct = 0;
for (int i = 0; i < NO_OF_CHARS; i++)
if (count[i] != 0)
max_distinct++;
return max_distinct;
}
int smallesteSubstr_maxDistictChar(string str){
int n = str.size(); // size of given string
// Find maximum distinct characters in any string
int max_distinct = max_distinct_char(str, n);
int minl = n; // result
// Brute force approach to find all substrings
for (int i=0 ;i<n ;i++){
for (int j=0; j<n; j++){
string subs = str.substr(i,j);
int subs_lenght = subs.size();
int sub_distinct_char = max_distinct_char(subs, subs_lenght);
// We have to check here both conditions together
// 1. substring's distinct characters is equal
// to maximum distinct characters
// 2. substring's length should be minimum
if (subs_lenght < minl && max_distinct == sub_distinct_char){
minl = subs_lenght;
}
}
}
return minl;
}
/* Driver program to test above function */
int main()
{
// Input String
string str = "AABBBCBB";
int len = smallesteSubstr_maxDistictChar(str);
cout << " The length of the smallest substring"
" consisting of maximum distinct "
"characters : " << len;
return 0;
}
/* Java program to find the length of the smallest
substring consisting of maximum distinct characters */
class GFG {
final static int NO_OF_CHARS = 256;
// Find maximum distinct characters in any string
static int max_distinct_char(String str, int n) {
// Initialize all character's count with 0
int count[] = new int[NO_OF_CHARS];
// Increase the count in array if a character
// is found
for (int i = 0; i < n; i++) {
count[str.charAt(i)]++;
}
int max_distinct = 0;
for (int i = 0; i < NO_OF_CHARS; i++) {
if (count[i] != 0) {
max_distinct++;
}
}
return max_distinct;
}
static int smallesteSubstr_maxDistictChar(String str) {
int n = str.length(); // size of given string
// Find maximum distinct characters in any string
int max_distinct = max_distinct_char(str, n);
int minl = n; // result
// Brute force approach to find all substrings
for (int i = 0; i < n; i++) {
for (int j = 0; j < n; j++) {
String subs = null;
if(i<j)
subs = str.substring(i, j);
else
subs = str.substring(j, i);
int subs_lenght = subs.length();
int sub_distinct_char = max_distinct_char(subs, subs_lenght);
// We have to check here both conditions together
// 1. substring's distinct characters is equal
// to maximum distinct characters
// 2. substring's length should be minimum
if (subs_lenght < minl && max_distinct == sub_distinct_char) {
minl = subs_lenght;
}
}
}
return minl;
}
/* Driver program to test above function */
static public void main(String[] args) {
// Input String
String str = "AABBBCBB";
int len = smallesteSubstr_maxDistictChar(str);
System.out.println(" The length of the smallest substring"
+ " consisting of maximum distinct "
+ "characters : "+len);
}
}
// This code is contributed by 29AjayKumar
# Python 3 program to find the length
# of the smallest substring consisting
# of maximum distinct characters
NO_OF_CHARS = 256
# Find maximum distinct characters
# in any string
def max_distinct_char(str, n):
# Initialize all character's
# count with 0
count = [0] * NO_OF_CHARS
# Increase the count in array
# if a character is found
for i in range(n):
count[ord(str[i])] += 1
max_distinct = 0
for i in range(NO_OF_CHARS):
if (count[i] != 0):
max_distinct += 1
return max_distinct
def smallesteSubstr_maxDistictChar(str):
n = len(str) # size of given string
# Find maximum distinct characters
# in any string
max_distinct = max_distinct_char(str, n)
minl = n # result
# Brute force approach to
# find all substrings
for i in range(n):
for j in range(n):
subs = str[i:j]
subs_lenght = len(subs)
sub_distinct_char = max_distinct_char(subs,
subs_lenght)
# We have to check here both conditions together
# 1. substring's distinct characters is equal
# to maximum distinct characters
# 2. substring's length should be minimum
if (subs_lenght < minl and
max_distinct == sub_distinct_char):
minl = subs_lenght
return minl
# Driver Code
if __name__ == "__main__":
# Input String
str = "AABBBCBB"
l = smallesteSubstr_maxDistictChar(str);
print( "The length of the smallest substring",
"consisting of maximum distinct",
"characters :", l)
# This code is contributed by ChitraNayal
/* C# program to find the length of the smallest
substring consisting of maximum distinct characters */
using System;
class GFG
{
static int NO_OF_CHARS = 256;
// Find maximum distinct characters in any string
static int max_distinct_char(String str, int n)
{
// Initialize all character's count with 0
int []count = new int[NO_OF_CHARS];
// Increase the count in array if a character
// is found
for (int i = 0; i < n; i++)
{
count[str[i]]++;
}
int max_distinct = 0;
for (int i = 0; i < NO_OF_CHARS; i++)
{
if (count[i] != 0)
{
max_distinct++;
}
}
return max_distinct;
}
static int smallesteSubstr_maxDistictChar(String str)
{
int n = str.Length; // size of given string
// Find maximum distinct characters in any string
int max_distinct = max_distinct_char(str, n);
int minl = n; // result
// Brute force approach to find all substrings
for (int i = 0; i < n; i++)
{
for (int j = 0; j < n; j++)
{
String subs = null;
if(i < j)
subs = str.Substring(i, str.Length-j);
else
subs = str.Substring(j, str.Length-i);
int subs_lenght = subs.Length;
int sub_distinct_char = max_distinct_char(subs, subs_lenght);
// We have to check here both conditions together
// 1. substring's distinct characters is equal
// to maximum distinct characters
// 2. substring's length should be minimum
if (subs_lenght < minl && max_distinct == sub_distinct_char)
{
minl = subs_lenght;
}
}
}
return minl;
}
/* Driver program to test above function */
static public void Main(String[] args)
{
// Input String
String str = "AABBBCBB";
int len = smallesteSubstr_maxDistictChar(str);
Console.WriteLine(" The length of the smallest substring"
+ " consisting of maximum distinct "
+ "characters : "+len);
}
}
// This code contributed by Rajput-Ji
<script>
// Javascript program to find the length
// of the smallest substring consisting
// of maximum distinct characters
let NO_OF_CHARS = 256;
// Find maximum distinct characters
// in any string
function max_distinct_char(str, n)
{
// Initialize all character's
// count with 0
let count = new Array(NO_OF_CHARS);
for(let i = 0; i < count.length; i++)
{
count[i] = 0;
}
// Increase the count in array if a
// character is found
for(let i = 0; i < n; i++)
{
count[str[i].charCodeAt(0)]++;
}
let max_distinct = 0;
for(let i = 0; i < NO_OF_CHARS; i++)
{
if (count[i] != 0)
{
max_distinct++;
}
}
return max_distinct;
}
function smallesteSubstr_maxDistictChar(str)
{
// Size of given string
let n = str.length;
// Find maximum distinct characters
// in any string
let max_distinct = max_distinct_char(str, n);
// Result
let minl = n;
// Brute force approach to find all
// substrings
for(let i = 0; i < n; i++)
{
for(let j = 0; j < n; j++)
{
let subs = null;
if (i < j)
subs = str.substring(i, j);
else
subs = str.substring(j, i);
let subs_lenght = subs.length;
let sub_distinct_char = max_distinct_char(
subs, subs_lenght);
// We have to check here both conditions together
// 1. substring's distinct characters is equal
// to maximum distinct characters
// 2. substring's length should be minimum
if (subs_lenght < minl &&
max_distinct == sub_distinct_char)
{
minl = subs_lenght;
}
}
}
return minl;
}
// Driver Code
let str = "AABBBCBB";
let len = smallesteSubstr_maxDistictChar(str);
document.write("The length of the smallest substring" +
" consisting of maximum distinct " +
"characters : " + len);
// This code is contributed by avanitrachhadiya2155
</script>
<?php
/* PHP program to find the length of the smallest
substring consisting of maximum distinct characters */
$NO_OF_CHARS=256;
// Find maximum distinct characters in any string
function max_distinct_char($str, $n)
{
global $NO_OF_CHARS;
// Initialize all character's count with 0
$count = array_fill(0, $NO_OF_CHARS, 0);
// Increase the count in array if a character
// is found
for ($i = 0; $i < $n; $i++)
$count[ord($str[$i])]++;
$max_distinct = 0;
for ($i = 0; $i < $NO_OF_CHARS; $i++)
if ($count[$i] != 0)
$max_distinct++;
return $max_distinct;
}
function smallesteSubstr_maxDistictChar($str)
{
$n = strlen($str); // size of given string
// Find maximum distinct characters in any string
$max_distinct = max_distinct_char($str, $n);
$minl = $n; // result
// Brute force approach to find all substrings
for ($i = 0 ; $i < $n ; $i++)
{
for ($j = 0; $j < $n; $j++)
{
$subs = substr($str, $i, $j);
$subs_lenght = strlen($subs);
$sub_distinct_char = max_distinct_char($subs, $subs_lenght);
// We have to check here both conditions together
// 1. substring's distinct characters is equal
// to maximum distinct characters
// 2. substring's length should be minimum
if ($subs_lenght < $minl &&
$max_distinct == $sub_distinct_char)
{
$minl = $subs_lenght;
}
}
}
return $minl;
}
/* Driver code */
// Input String
$str = "AABBBCBB";
$len = smallesteSubstr_maxDistictChar($str);
echo " The length of the smallest substring"
." consisting of maximum distinct characters : ".$len;
// This code is contributed by mits
?>
Output The length of the smallest substring consisting of maximum distinct characters : 5
Time Complexity : O(n3)
Auxiliary Space: O(n)
Method 2 (Efficient)
- Count all distinct characters in given string.
- Maintain a window of characters. Whenever the window contains all characters of given string, we shrink the window from left side to remove extra characters and then compare its length with smallest window found so far.
Implementation:
C++
/* C++ program to find the length of the smallest
substring consisting of maximum distinct characters */
#include <bits/stdc++.h>
using namespace std;
// A function which accepts a string and returns length of
// the smallest substring consisting of maximum distinct
// characters
int smallesteSubstr_maxDistictChar(string str)
{
// to get the number of unique characters
unordered_set<char> st;
// traverse the string once and store the characters
for (int i = 0; i < str.length(); i++)
st.insert(str[i]);
// number of unique characters
int unique = st.size();
unordered_map<char, int> mp;
// to store the result
int res = INT_MAX;
int j = 0; // starting index of window
for (int i = 0; i < str.length(); i++) {
// add the current character in window
mp[str[i]]++;
// while number of distinct elements in the map is
// equal to unique characters and starting element
// of the window has frequency more than one we keep
// reducing its frequency and increasing the
// starting point of the window
while (mp.size() == unique && mp[str[j]] > 1) {
mp[str[j]]--;
j++;
}
// if size of map is equal to unique elements update
// the result
if (mp.size() == unique)
res = min(i - j + 1, res);
}
return res;
}
/* Driver program to test above function */
int main()
{
// Input String
string str = "AABBBCBB";
int len = smallesteSubstr_maxDistictChar(str);
cout << " The length of the smallest substring"
" consisting of maximum distinct "
"characters : "
<< len;
return 0;
}
// This code was contributed by Abhijeet Kumar(abhijeet19403)
/* Java program to find the length of the smallest
substring consisting of maximum distinct characters */
import java.util.*;
class GFG {
static final int MAX_CHARS = 256;
// Find maximum distinct characters in any string
static int max_distinct_char(String str, int n)
{
// Initialize all character's count with 0
int count[] = new int[MAX_CHARS];
int max_distinct = 0;
// Increase the count of max_distinct if a character
// is found to have a frequency of 1
for (int i = 0; i < n; i++) {
count[str.charAt(i)]++;
if (count[str.charAt(i)] == 1)
max_distinct++;
}
return max_distinct;
}
// A function which accepts a string and returns length
// of the smallest substring consisting of maximum distinct
// characters
static int smallestSubstr_maxDistictChar(String str)
{
int n = str.length();
// number of unique characters
int unique = max_distinct_char(str, n);
// to store the result
int res = Integer.MAX_VALUE;
Map<Character, Integer> mp
= new HashMap<Character, Integer>();
int j = 0; // starting index of window
for (int i = 0; i < str.length(); i++) {
// add the current character in window
char c = str.charAt(i);
if (mp.containsKey(c))
mp.put(c, mp.get(c) + 1);
else
mp.put(c, 1);
// while no. of distinct elements in the map is
// equal to unique characters and starting
// element of the window has frequency more than
// one we keep reducing its frequency and
// increasing the starting point of the window
while (mp.size() == unique
&& mp.get(str.charAt(j)) > 1) {
mp.put(str.charAt(j),
(mp.get(str.charAt(j)) - 1));
j++;
}
// if size of map is equal to unique elements
// update the result
if (mp.size() == unique)
res = Math.min(i - j + 1, res);
}
return res;
}
/* Driver program to test above function */
static public void main(String[] args)
{
// Input String
String str = "AABBBCBB";
int len = smallestSubstr_maxDistictChar(str);
System.out.println(
" The length of the smallest substring"
+ " consisting of maximum distinct "
+ "characters : " + len);
}
}
// This code is contributed by Abhijeet Kumar(abhijeet19403)
import sys
import math
class GFG :
MAX_CHARS = 256
# Find maximum distinct characters in any string
@staticmethod
def max_distinct_char( str, n) :
# Initialize all character's count with 0
count = [0] * (GFG.MAX_CHARS)
max_distinct = 0
# Increase the count of max_distinct if a character
# is found to have a frequency of 1
i = 0
while (i < n) :
count[ord(str[i])] += 1
if (count[ord(str[i])] == 1) :
max_distinct += 1
i += 1
return max_distinct
# A function which accepts a string and returns length
# of the smallest substring consisting of maximum distinct
# characters
@staticmethod
def smallestSubstr_maxDistictChar( str) :
n = len(str)
# number of unique characters
unique = GFG.max_distinct_char(str, n)
# to store the result
res = sys.maxsize
mp = dict()
j = 0
# starting index of window
i = 0
while (i < len(str)) :
# add the current character in window
c = str[i]
if ((c in mp.keys())) :
mp[c] = mp.get(c) + 1
else :
mp[c] = 1
# while no. of distinct elements in the map is
# equal to unique characters and starting
# element of the window has frequency more than
# one we keep reducing its frequency and
# increasing the starting point of the window
while (len(mp) == unique and mp.get(str[j]) > 1) :
mp[str[j]] = (mp.get(str[j]) - 1)
j += 1
# if size of map is equal to unique elements
# update the result
if (len(mp) == unique) :
res = min(i - j + 1,res)
i += 1
return res
# Driver program to test above function
@staticmethod
def main( args) :
# Input String
st = "AABBBCBB"
len = str(GFG.smallestSubstr_maxDistictChar(st))
print(" The length of the smallest substring" + " consisting of maximum distinct " + "characters : " + len)
if __name__=="__main__":
GFG.main([])
# This code is contributed by adityaburujwale.
/* C# program to find the length of the smallest
substring consisting of maximum distinct characters */
using System;
using System.Collections.Generic;
class GFG
{
static int MAX_CHARS = 256;
// Find maximum distinct characters in any string
static int max_distinct_char(String str, int n)
{
// Initialize all character's count with 0
int[] count = new int[MAX_CHARS];
int max_distinct = 0;
// Increase the count of max_distinct if a character
// is found to have a frequency of 1
for (int i = 0; i < n; i++) {
count[str[i]]++;
if (count[str[i]] == 1)
max_distinct++;
}
return max_distinct;
}
static int smallestSubstr_maxDistictChar(String str)
{
int n = str.Length;
// number of unique characters
int unique = max_distinct_char(str, n);
// to store the result
int res = int.MaxValue;
Dictionary<char, int> mp = new Dictionary<char, int>();
int j = 0; // starting index of window
for (int i = 0; i < n; i++) {
// add the current character in window
if (mp.ContainsKey(str[i]))
mp[str[i]]++;
else
mp.Add(str[i], 1);
// while no. of distinct elements in the map is
// equal to unique characters and starting
// element of the window has frequency more than
// one we keep reducing its frequency and
// increasing the starting point of the window
while (mp.Count == unique && mp[str[j]] > 1)
{
mp[str[j]]--;
j++;
}
// if size of map is equal to unique elements
// update the result
if (mp.Count == unique)
res = Math.Min(i - j + 1, res);
}
return res;
}
/* Driver program to test above function */
static public void Main(String[] args)
{
// Input String
String str = "AABBBCBB";
int len = smallestSubstr_maxDistictChar(str);
Console.WriteLine(" The length of the smallest substring"
+ " consisting of maximum distinct "
+ "characters : "+len);
}
}
// This code contributed by Abhijeet Kumar(abhijeet19403)
var MAX_CHARS = 256;
// Find maximum distinct characters in any string
function max_distinct_char(str, n)
{
// Initialize all character's count with 0
var count = Array(MAX_CHARS).fill(0);
var max_distinct = 0;
// Increase the count of max_distinct if a character
// is found to have a frequency of 1
var i=0;
for (i; i < n; i++)
{
count[str.charAt(i).charCodeAt(0)]++;
if (count[str.charAt(i).charCodeAt(0)] == 1)
{
max_distinct++;
}
}
return max_distinct;
}
// A function which accepts a string and returns length
// of the smallest substring consisting of maximum distinct
// characters
function smallestSubstr_maxDistictChar(str)
{
var n = str.length;
// number of unique characters
var unique = max_distinct_char(str, n);
// to store the result
var res = Number.MAX_VALUE;
var mp = new Map();
var j = 0;
// starting index of window
var i=0;
for (i; i < str.length; i++)
{
// add the current character in window
var c = str.charAt(i);
if (mp.has(c))
{
mp.set(c,mp.get(c) + 1);
}
else
{
mp.set(c,1);
}
// while no. of distinct elements in the map is
// equal to unique characters and starting
// element of the window has frequency more than
// one we keep reducing its frequency and
// increasing the starting point of the window
while (mp.size == unique && mp.get(str.charAt(j)) > 1)
{
mp.set(str.charAt(j),(mp.get(str.charAt(j)) - 1));
j++;
}
// if size of map is equal to unique elements
// update the result
if (mp.size == unique)
{
res = Math.min(i - j + 1,res);
}
}
return res;
}
// Driver program to test above function
// Input String
var str = "AABBBCBB";
var len = smallestSubstr_maxDistictChar(str);
console.log(" The length of the smallest substring" + " consisting of maximum distinct " + "characters : " + len);
// This code is contributed by sourabhdalal0001.
Output The length of the smallest substring consisting of maximum distinct characters : 5
Time Complexity: O(n), As we doing linear operations on string.
Auxiliary Space: O(n), As constant extra space is used. The size of set and map can only go upto a maximum size of 256 which is a constant thus the extra space used is also constant.
Please refer Smallest window that contains all characters of string itself more details.
Asked In : DailyHunt
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