[Project Euler] Problem 9

A Pythagorean triplet is a set of three natural numbers, a b c, for which,

a² + b² = c²

For example, 3² + 4² = 9 + 16 = 25 = 5².

There exists exactly one Pythagorean triplet for which a + b + c = 1000.
Find the product abc.

寻找和为1000毕达哥拉斯三元数组，求它们的积

由于a b c，我们容易得到a的范围

a < 1000/(1+1+1.414); 估算有 a < 300;

#include <iostream>
using namespace std;

int main(){
    for(int a=1; a<300; a++){
        for(int b=(1000-a)/2; b>a; b--){
            if(a*a+b*b == (1000-a-b)*(1000-a-b)){
                cout << a*b*(1000-a-b) << endl;
                return 0;
            }
        }
    }
    return 0;
}

事实上，我们不能确认这样的数只有一组，所以中间那个 “return 0;”应该去掉