先讓啊、三邊邊長a，b，c按從小到大順序排列，然後再用兩邊之和大於第三邊，兩邊之差小於第三邊來判斷

#include <iostream>
#include <cstdio>
#include <cstring>
#include <cmath>
#include <cstdlib>
#include <set>
#include <algorithm>
using namespace std;
int main ()
{
	int n;
	double a,b,c,minn,t;
	scanf("%d",&n);
	while(n--)
	{
		scanf("%lf%lf%lf",&a,&b,&c);
		if(a>b)
		{t=a;a=b;b=t;}
		if(a>c)
		{t=a;a=c;c=t;}
		if(b>c)
		{t=b;b=c;c=t;}
		if(a+b>c && c-b<a)
			printf("YES\n");
		else
			printf("NO\n");
	}
	return 0;
}