#include <iostream>
using namespace std;
int main()
{
    int a , b , c;
    cin >> a >> b >> c;
    if((a + b > c)&&(a + c > b)&&(b + c > a))
    {
        cout << "yes";
    }
    else
    {
        cout << "no";
    }
    return 0;
}

#include <iostream>
using namespace std;
int main()
{
    int a,b,h;
    cin >> a >> b >> h;
    if (((a+b) >h)&&((b+h)>a)&&((a+h)>b))//这里要用并且&&判断
        cout << "yes";
    else
        cout << "no";
    return 0;
}

#include<bits/stdc++.h>
using namespace std;
int main()
{
    int a[5];
    cin>>a[1]>>a[2]>>a[3];
    sort(a+1,a+4);
    if (a[1]+a[2]>a[3])
    {
        cout<<"yes";
    }
    else
    {
        cout<<"no";
    }
    return 0;
} 

直接排序

#include <iostream>
#include <cstdio>
#include <cstring>
using namespace std;
int main() {
	int a, b, c;
	cin >> a >> b >> c;
	if (a + b > c && a + c > b && b + c > a) {
    	
		cout << "yes";
	}
	else {
		cout <<"no";
	}
	return 0;
}