四平方和定理

#include<cstdio>

#include<cstdlib>

#include<cmath>

#define FOR(i,a,b) for(i=(a);i<=(b);i++)

using namespace std;

int i,j,n;

int c1(int t){int R=(int)sqrt(t);return R*R==t;}

int c2(int t){FOR(i,1,(int)sqrt(t)) if (c1(t-i*i)) return 1;return 0;}

int c3(int t){FOR(j,1,(int)sqrt(t)) if (c2(t-j*j)) return 1;return 0;}

int main()

{

scanf("%d",&n);

if (c1(n)) {printf("1\n");return 0;}

if (c2(n)) {printf("2\n");return 0;}

if (c3(n)) {printf("3\n");return 0;}

printf("4\n");

}

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