[C]Armstrong Number

 

 

// 1234 = 1^4 + 2^4 + 3^4 + 4^4;
// 341 = 3^3 + 4^3 + 1^3
// 类似于水仙花数

#include <stdio.h>
#include <math.h>
int digitCount(int n) { //此函数用于获取整数的位数
    int i = 0;
    do {
        n = n / 10;
        i++;
    } while ( n > 0 );
    return i;
}

int isArmstrong(int n) {
    int digitNum = digitCount(n);
    int sum = 0;
    int temp = n;
    while (n > 0) {
        sum += pow(n % 10, digitNum);
        n = n / 10;
    } //n 已经不再是那个n
    return sum == temp;
}

int main() {
    int i;
    for ( i = 1; i < 5000; ++i ) {
        if (isArmstrong(i)) {
            printf("%d is Armstrong number\n", i);
        }
    }
    return 0;
}