POJ 1442 Black Box -优先队列

来源：互联网发布：软件开发方法学编辑：程序博客网时间：2024/04/29 03:39

优先队列。。刚开始用蠢办法，经过一个vector容器中转，这么一来一回这么多趟，肯定超时啊。

超时代码如下：

#include <iostream>#include <cstdio>#include <cstring>#include <cmath>#include <algorithm>#include <cstdlib>#include <string>#include <vector>#include <map>#include <queue>#include <functional>using namespace std;#define N 30003priority_queue<int,vector<int>,greater<int> > que;int A[N];vector<int> tmp;int main(){    int m,n,i,j,th,u,k,h;    while(scanf("%d%d",&m,&n)!=EOF)    {        th = 0;        for(i=0;i<m;i++)            scanf("%d",&A[i]);        j = 0;        k = 0;        for(i=0;i<n;i++)        {            scanf("%d",&u);            while(j<u)            {                que.push(A[k++]);                j++;            }            th++;            for(h=1;h<th;h++)            {                tmp.push_back(que.top());                que.pop();            }            printf("%d\n",que.top());            for(h=0;h<tmp.size();h++)                que.push(tmp[h]);            tmp.clear();        }    }    return 0;}

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后来看了网上某位大牛的，说是用两个优先队列，一个从大到小的，一个从小到大的，元素在这两个中间中转，可以大大缩短时间。

代码：

#include <iostream>#include <cstdio>#include <cstring>#include <cmath>#include <algorithm>#include <string>#include <vector>#include <map>#include <queue>#include <functional>using namespace std;#define N 30003priority_queue<int,vector<int>,greater<int> > StoBig;  //从小到大排，先出小的priority_queue<int,vector<int>,less<int> > BtoSmall;    //从大到小排，先出大的int A[N];int main(){    int m,n,i,j,th,u,k,h;    while(scanf("%d%d",&m,&n)!=EOF)    {        th = 0;        for(i=0;i<m;i++)            scanf("%d",&A[i]);        j = 0;        for(i=0;i<n;i++)        {            scanf("%d",&u);            while(j<u)                BtoSmall.push(A[j++]);            th++;            while(BtoSmall.size() >= th)  //语句1            {                StoBig.push(BtoSmall.top());                BtoSmall.pop();            }            printf("%d\n",StoBig.top());            BtoSmall.push(StoBig.top());   //还给它，保证语句1能够成立            StoBig.pop();        }    }    return 0;}

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