PAT Advanced Level 1057

来源：互联网发布：域名后缀产生编辑：程序博客网时间：2024/05/24 06:36

题目地址：http://pat.zju.edu.cn/contests/pat-a-practise/1057

解题感悟：主要解决超时问题。参考网络大神解题报告，使用到了树形数组，膜拜

代码如下：

#include<stdio.h>#include<cstring>#include<iostream>#include<string>using namespace std;const int N=100005;int c[N];int lowbit(int i){return i&(-i);}void add(int pos,int value){while(pos<N){c[pos]+=value;pos+=lowbit(pos);}}int sum(int pos){int res=0;while(pos>0){res+=c[pos];pos-=lowbit(pos);}return res;}int find(int value){int l=0,r=N-1,median,res;while(l<r-1){if((l+r)%2==0)median=(l+r)/2;elsemedian=(l+r-1)/2;res=sum(median);if(res<value)l=median;elser=median;}return l+1;}int main(){char ss[20];int stack[N],top=0,n,pos;memset(c,0,sizeof(c));scanf("%d",&n);while(n--){scanf("%s",ss);if(ss[1]=='u'){scanf("%d",&pos);stack[++top]=pos;add(pos,1);}else if(ss[1]=='o'){if(top==0){printf("Invalid\n");continue;}int out=stack[top];add(out,-1);printf("%d\n",stack[top--]);}else if(ss[1]=='e'){if(top==0){printf("Invalid\n");continue;}int res;if(top%2==0)res=find(top/2);elseres=find((top+1)/2);printf("%d\n",res);}else{printf("Invalid\n");}}return 0;}

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