Stones（优先队列）

小咪咪 2022-08-01 11:22 109阅读 0赞

# Stones #

**Time Limit: 5000/3000 MS (Java/Others)    Memory Limit: 65535/32768 K (Java/Others)  
Total Submission(s): 1272    Accepted Submission(s): 784**

Problem Description

Because of the wrong status of the bicycle, Sempr begin to walk east to west every morning and walk back every evening. Walking may cause a little tired, so Sempr always play some games this time.   
There are many stones on the road, when he meet a stone, he will throw it ahead as far as possible if it is the odd stone he meet, or leave it where it was if it is the even stone. Now give you some informations about the stones on the road, you are to tell me the distance from the start point to the farthest stone after Sempr walk by. Please pay attention that if two or more stones stay at the same position, you will meet the larger one(the one with the smallest Di, as described in the Input) first.

Input

In the first line, there is an Integer T(1<=T<=10), which means the test cases in the input file. Then followed by T test cases.   
For each test case, I will give you an Integer N(0<N<=100,000) in the first line, which means the number of stones on the road. Then followed by N lines and there are two integers Pi(0<=Pi<=100,000) and Di(0<=Di<=1,000) in the line, which means the position of the i-th stone and how far Sempr can throw it.

Output

Just output one line for one test case, as described in the Description.

Sample Input

2
    2
    1 5
    2 4
    2
    1 5
    6 6

Sample Output

11
    12

Author

Sempr|CrazyBird|hust07p43

Source

[HDU 2008-4 Programming Contest][]

**是奇数就扔，是偶数就忽略！记住就是在同一点的石头不算一个**

**有几个算几个！优先队列！**

**关于优先队列的详解看这里！[优先队列][Link 1]**

#include<cstdio>
    #include<iostream>
    #include<queue>
    #include<vector>
    using namespace std;
    struct node
    {
        int pos;
        int dis;
    };
    struct cmp{
        bool operator () (node a,node b){
            if(a.pos!=b.pos)
                return a.pos>b.pos;
            else
                return a.dis>b.dis;
        }
    };
    int main()
    {
        priority_queue<node,vector<node>,cmp>s;
        int t,n1,num,result;
        cin>>t;
        while(t--)
        {
            node n;
            cin>>n1;
            while(n1--)
            {
                cin>>n.pos>>n.dis;
                s.push(n);
            }
            num=1;
            while(!s.empty())
            {
                n=s.top();
                s.pop();
                if(num&1)
                {
                    n.pos+=n.dis;
                    s.push(n);
                }
                num++;
                result=n.pos;
            }
            cout<<result<<endl;
        }
    }

struct cmp\{  
    bool operator () (node a,node b)\{  
        if(a.pos!=b.pos)  
            return a.pos>b.pos;  
        else  
            return a.dis>b.dis;  
    \}  
\};

**这里要说一下，为什么这个明明排序是头大尾小，为什么输出是**

**头小尾大呢？**

**![Image 1][]**

**看这个吧，可能与这个机制有关记住就行了！**

[HDU 2008-4 Programming Contest]: http://acm.hdu.edu.cn/search.php?field=problem&key=HDU+2008-4+Programming+Contest&source=1&searchmode=source
[Link 1]: http://blog.csdn.net/baidu_23955875/article/details/46604583
[Image 1]: