题目链接

题面：

题意：
给定ac,ad,bc,bd 的长度，问是AB//CD ，还是AB//DC

题解：
根据 梯形对角线长度和一定大于两腰长度和。

#include<iostream>
#include<cstdio>
#include<cstdlib>
#include<algorithm>
#include<cstring>
#include<cmath>
#include<string>
#include<queue>
#include<bitset>
#include<map>
#include<unordered_map>
#include<set>
#define ui unsigned int
#define ll long long
#define llu unsigned ll
#define ld long double
#define pr make_pair
#define pb push_back
#define lc (cnt<<1)
#define rc (cnt<<1|1)
#define len(x) (t[(x)].r-t[(x)].l+1)
#define tmid ((l+r)>>1)
using namespace std;

const int inf=0x3f3f3f3f;
const ll lnf=0x3f3f3f3f3f3f3f3f;
const double dnf=1e18;
const int mod=1e9+7;
const double eps=1e-8;
const double pi=acos(-1.0);
const int hp=13331;
const int maxn=1000100;
const int maxm=100100;
const int up=100100;

int main(void)
{
    int ac,ad,bc,bd,t;
    scanf("%d",&t);
    while(t--)
    {
        scanf("%d%d%d%d",&ac,&ad,&bc,&bd);
        if(ac+bd>ad+bc) printf("AB//DC\n");
        else if(ac+bd<ad+bc) printf("AB//CD\n");
    }
    return 0;
}