C++输出倒立三角形

#include <iostream>
using namespace std;

int main(){
	for (int i = 1;i <= 4;i ++){
		for (int j = 2;j <= i;j ++) cout << 1;
		for (int k = 2 * i - 1;k <= 7;k ++) cout << 0;
		for (int l = 2;l <= i;l ++) cout << 1;
		cout << endl;
	}
	return 0;
}