Median（vector+二分）

最新推荐文章于 2023-03-05 21:51:42 发布

weixin_30458043

最新推荐文章于 2023-03-05 21:51:42 发布

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原文链接：http://www.cnblogs.com/yuyixingkong/p/3956292.html

本文介绍了一种使用vector容器高效查找中位数的方法，包括添加和删除操作后的更新步骤，以及处理边界情况的技巧。

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Median

Time Limit: 5 Seconds Memory Limit: 65536 KB

The median of m numbers is after sorting them in order, the middle one number of them if m is even or the average number of the middle 2 numbers if m is odd. You have an empty number list at first. Then you can add or remove some number from the list.

For each add or remove operation, output the median of the number in the list please.

Input

This problem has several test cases. The first line of the input is an integer T (0<T<=100) indicates the number of test cases. The first line of each test case is an integer n (0<n<=10000) indicates the number of operations. Each of the next n lines is either "add x" or "remove x"(-2³¹<=x<2³¹) indicates the operation.

Output

For each operation of one test case: If the operation is add output the median after adding x in a single line. If the operation is remove and the number x is not in the list, output "Wrong!" in a single line. If the operation is remove and the number x is in the list, output the median after deleting x in a single line, however the list is empty output "Empty!".

Sample Input

2
7
remove 1
add 1
add 2
add 1
remove 1
remove 2
remove 1
3
add -2
remove -2
add -1

Sample Output

Wrong!
1
1.5
1
1.5
1
Empty!
-2
Empty!
-1

Hint

if the result is an integer DO NOT output decimal point. And if the result is a double number , DO NOT output trailing 0s.

题意：找中位数，由于数据比较大，用到了vector容器，

我也不会用，比赛前看过一点，可是不知道怎么用，so。。。比赛完，借大神的代码来观摩下，哈哈。我发现这个真的很好用。我一定要把他学会！！！

ps：http://acm.zju.edu.cn/onlinejudge/showProblem.do?problemId=4736

#include<iostream>
#include<cstdio>
#include<vector>
#include<cstring>
using namespace std;
vector<int>vet;
int deal(int x)
{
    int left=0,right=vet.size()-1;
    while(left<=right)
    {
        int mid=(left+right)/2;
        if(vet[mid]==x)
        {
            return mid;
        }
        else if(vet[mid]>x)
        {
            right=mid-1;
        }
        else
        {
            left=mid+1;
        }
    }
    return -1;
}
int erfen(int x)
{
    if(vet.size()==0) return 0;
    if(x<vet[0]) return 0;
    if(x>vet[vet.size()-1]) return vet.size();
    int left=0,right=vet.size()-1,k=-1;
    while(left<=right)
    {
        int mid=(left+right)/2;
        if(vet[mid]>=x&&vet[mid-1]<=x)
        {
            return mid;
        }
        else if(vet[mid]<=x&&vet[mid+1]>=x)
        {
            return mid+1;
        }
        else if(vet[mid]>x)
        {
            right=mid-1;
        }
        else left=mid+1;
    }
}
int main()
{
    int text;
    scanf("%d",&text);
    while(text--)
    {
        int n;
        scanf("%d",&n);
        vet.clear();
        vector<int>::iterator it=vet.begin();
        while(n--)
        {

            char ch[30];
            int x;
            scanf("%s%d",ch,&x);
            if(ch[0]=='r')
            {
                if(vet.size()==0)
                {
                    printf("Wrong!\n");
                    continue;
                }
                else
                {
                    int tmp=deal(x);
                    if(tmp==-1)
                    {
                        printf("Wrong!\n");
                        continue;
                    }
                    else
                    {
                        it=vet.begin();
                        vet.erase((it+tmp));
                        int len=vet.size();
                        if(len==0)
                        {
                            printf("Empty!\n");
                            continue;
                        }
                        else if(len%2==1)
                            cout<<vet[len/2]<<endl;
                        else
                        {
                            long long ans=(long long)vet[len/2]+(long long)vet[len/2-1];
                            if(ans%2==0)
                                printf("%lld\n",ans/2);
                            else
                            {
                                double sum=ans/2.0;
                                printf("%.1lf\n",sum);
                            }
                        }

                    }
                }
            }
            else
            {
                int tmp=erfen(x);
                it=vet.begin();
                vet.insert((it+tmp),x);
                int len=vet.size();
                if(len%2==1)
                    printf("%d\n",vet[len/2]);
                else
                {
                    long long ans=(long long)vet[len/2]+(long long)vet[len/2-1];
                    if(ans%2==0)
                        printf("%lld\n",ans/2);
                    else
                    {
                        double sum=ans/2.0;
                        printf("%.1lf\n",sum);
                    }
                }
            }
        }
    }
    return 0;
}