Ultraviolet A 11490-just another problem (Mathematics)

Link: Ultraviolet A 11490-just another problem

N soldiers should be arranged into a square matrix, and the square matrix should be as big as possible. Therefore, two square areas will be blank in the middle of the square, and the thickness of the blank area should be the same, that is, the four sides of a square have X rows or columns in the corresponding direction.

Solution: According to the question, we can know that X (6x + 7R) = n, x is the thickness, and r is the side length of a square. Then enumerate X, X is the factor of N.

#include <cstdio>#include <cstring>#include <cmath>typedef long long ll;const ll MOD = 100000007;ll n;int main () {    while (scanf("%lld", &n) == 1 && n) {        int cnt = 0;        ll m = sqrt(n+0.5);        for (ll i = 1; i <= m; i++) {            if (n%i)                continue;            ll j = n / i;            j -= 6 * i;            if (j%7 || j <= 0)                continue;            ll r = (j/7) % MOD;            ll ans = (2 * r * r) % MOD;            if (ans == 0)                continue;            cnt++;            printf("Possible Missing Soldiers = %lld\n", ans);        }        if (cnt == 0)            printf("No Solution Possible\n");        printf("\n");    }    return 0;}