C Program to Print Armstrong Numbers Between 1 to 1000 Last Updated : 23 Apr, 2023 Comments Improve Suggest changes Like Article Like Report Armstrong numbers are those numbers in which the sum of digits raised to the power of a number of digits in that number will be equal to the number itself. Here will see how to build a C Program to Display Armstrong numbers between 1 to 1000. Example: 153 13 + 53 + 33 1 + 125 + 27 = 153Approach 1:Count the number of digits in the number.Then calculate the sum of digits raised to the power of the number of digits in that number.Check whether it is equal to the number, if yes then print it. C // C Program to Display Armstrong // numbers between 1 to 1000 #include <math.h> #include <stdio.h> int main() { int i, sum, num, count = 0; printf( "All Armstrong number between 1 and 1000 are:\n"); // This loop will run for 1 to 1000 for (i = 1; i <= 1000; i++) { num = i; // Count number of digits. while (num != 0) { num /= 10; count++; } num = i; sum = pow(num % 10, count) + pow((num % 100 - num % 10) / 10, count) + pow((num % 1000 - num % 100) / 100, count); // Check for Armstrong Number if (sum == i) { printf("%d ", i); } count = 0; } } OutputAll Armstrong number between 1 and 1000 are: 1 2 3 4 5 6 7 8 9 153 370 371 407 Time Complexity: O(n * k) where n is the range of numbers to be checked (1 to 1000 in this case) and k is the maximum number of digits in any number in the range (3 in this case). This is because the loop runs for each number in the range and for each number, we calculate the sum of its digits raised to the power of k. Space Complexity: O(1) as we are only using a constant amount of extra space for variables to store the count, sum, and current number being checked. Approach 2:All one-digit numbers are Armstrong numbers. C // C Program to Display Armstrong // numbers between 1 to 1000 #include <stdio.h> #include <math.h> int main() { int i, digit1, digit2, digit3, sum, num; printf("All Armstrong number between 1 and 1000 are:\n"); // This loop will run for 1 to 1000 for (i = 1; i <= 1000; i++) { num = i; // All single digit numbers are Armstrong number. if (num <= 9) { printf("%d ", num); } else { sum = pow(num % 10, 3) + pow((num % 100 - num % 10) / 10, 3) + pow((num % 1000 - num % 100) / 100, 3); if (sum == i) { printf("%d ", i); } } } } OutputAll Armstrong number between 1 and 1000 are: 1 2 3 4 5 6 7 8 9 153 370 371 407 Comment More infoAdvertise with us Next Article C Program to Print Armstrong Numbers Between 1 to 1000 P pushpamkjha14 Follow Improve Article Tags : C Programs C Language Similar Reads C Programming Language Tutorial C is a general-purpose mid-level programming language developed by Dennis M. Ritchie at Bell Laboratories in 1972. 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