题目链接：uva 11490 - Just Another Problem

题目大意：有n个士兵，要排列成一个方阵，要求方阵尽量大，于是在方正的中间会空出两个正方形的区域，空出来的局域要求厚度相同，即正方形的四条边向相应方向均再有x行或者列。

解题思路：根据题意可以知道x(6x+7r)=n,x为厚度，r为正方形的边长。接着枚举x，x是n的因子。

#include 
   
     #include 
    
      #include 
     
       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; }