【AOJ 1241】Lagrange's Four-Square Theorem
問題
Lagrange's Four-Square Theorem | Aizu Online Judge
方針
- 全部探索する.
コード
#include <iostream> using namespace std; signed main(){ int n; while(cin >> n, n){ int cnt = 0; for(int i = 1 ; i * i <= n ; i++){ if(i*i == n) cnt++; for(int j = i ; j * j <= n ; j++){ if(i*i + j*j == n) cnt++; for(int k = j ; k * k <= n ; k++){ if(i*i + j*j + k*k == n) cnt++; for(int l = k ; l * l <= n ; l++){ if(i*i + j*j + k*k + l*l == n) cnt++; } } } } cout << cnt << endl; } }