#include <stdio.h>
#include <stdio.h>
 
int isom(int n) {
    int sum = 0;
 
    for (int i = 0; i <= n; i++) {
        int sq = i * i;     // 二乗
        int mod = 1;
        int x = i;
 
        // iの桁数に応じた10の累乗を作る
        if (i == 0) mod = 10;
        else {
            while (x > 0) {
                mod *= 10;
                x /= 10;
            }
        }
 
        // 二乗の末尾が同じなら自己同形数
        if (sq % mod == i) {
            sum += i;
        }
    }
 
    return sum;
}
int main(void) {
    printf("%d\n", isom(10));  // → 12
    printf("%d\n", isom(99));  // → 113
    return 0;
}
 
 
 

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