PAT A1057 分块思想

使用的就是分块思想，之前写过总结，所以不再赘述；
代码如下：

#include<iostream>
#include<stdlib.h>
#include<stdio.h>
#include<stack>
#include<cstring>
using namespace std;
const int maxn=100010;
const int sqrN=316;
stack<int>st;
int block[sqrN];
int table[maxn];

void peekMedian(int K){
    int sum=0;
    int idx=0;
    while(sum+block[idx]<K){
        sum+=block[idx++];
    }
    int num=idx*sqrN;
    while(sum+table[num]<K){
        sum+=table[num++];
    }
    printf("%d\n",num);
}

void push(int x){
    st.push(x);
    block[x/sqrN]++;
    table[x]++;
}

void pop(){
    int x=st.top();
    st.pop();
    block[x/sqrN]--;
    table[x]--;
    printf("%d\n",x);
}

int main(){
    int x,query;
    memset(block,0,sizeof(block));
    memset(table,0,sizeof(table));
    char cmd[20];
    scanf("%d",&query);
    for(int i=0;i<query;i++){
        scanf("%s",cmd);
        if(strcmp(cmd,"Push")==0){
            scanf("%d",&x);
            push(x);
        }else if(strcmp(cmd,"Pop")==0){
            if(st.empty()==true){
                printf("Invalid\n");
            }else{
                pop();
            }
        }else{
            if(st.empty()==true){
                printf("Invalid\n");
            }else{
                int K=st.size();
                if(K%2==1)
                    K=(K+1)/2;
                else
                    K=K/2;
                peekMedian(K);
            }
        }
    }
    system("pause");
    return 0;
}