Python的哦~

for a in range(3,21):
    for b in range(4,21):
        for c in range(5,21):
            if a**2+b**2==c**2 and a<=b:
                print(a,b,c)

#include <iostream>
using namespace std;
int main()
{
    int a,b,c;
    for(a=1;a<=20;a++)for(b=20;b>=a;b--)for(c=20;c>=b;c--){
        if(a*a+b*b==c*c){
            cout<<a<<" "<<b<<" "<<c<<endl;
        }
    }
    return 0;
}

c++

using namespace std;
int main(){
	int a,b,c;
	for(a=1;a<=20;a++){
		for(b=20;b>=a;b--){
			for(c=20;c>=b;c--){
				if(a*a+b*b==c*c && c!=20){
					cout<<a<<" "<<b<<" "<<c<<endl;
				}
				if(a*a+b*b==c*c && c==20){
					cout<<a<<" "<<b<<" "<<c;
				}
				}
			}
		}
	return 0;
}

#include <bits/stdc++.h>

using namespace std;
int A,B,C;
int main ()
{
        for(int a=1;a<=20;a++){
            A=pow(a,2);
            for(int c=3;c<=20;c++){
                C=pow(c,2);
                for(int b=a;b<=20;b++){
                    B=pow(b,2);
                if(C==A+B && a<=b && b<=c ){
                    cout<<a<<" "<<b<<" "<<c<<endl;
                }
            }
        }
    }
    return 0;
}