HDU 2852 KiKi's K-Number【 树状数组 二分 】

题意：给出m个操作，
0：是增加一个数,add(x,1)
1:是删除一个指定的数，这个是看sum(x) - sum(x-1)是否为0，为0的话则不存在，不为0的话，则add(x,-1)
2：是查询比x大的数中第k大的数，
先求出比x小的个数s,假设比x大的数中第k大的数为y,
那么比y小的个数有s+k个
二分y的值来找

#include<iostream>  
#include<cstdio>  
#include<cstring> 
#include <cmath> 
#include<stack>
#include<vector>
#include<map> 
#include<set>
#include<queue> 
#include<algorithm>  
using namespace std;

typedef long long LL;
const int INF = (1<<30)-1;
const int mod=1000000007;
const int maxn=100005;

int a[maxn],c[maxn];
int k;

int lowbit(int x){ return x &(-x);}

int sum(int x){
    int ret=0;
    while(x>0){
        ret+=c[x];x-=lowbit(x);
    }
    return ret;
}

void add(int x,int d){
    while(x<maxn){
        c[x]+=d;x+=lowbit(x);
    }
}

int solve(int x){
    int v=x;
    int s=sum(x);
    int kk=k+s;
    int lb=1,ub=maxn,mid;
    
    for(int i=1;i<=100;i++){
        mid=(lb+ub)/2;
        if(sum(mid) < kk) lb =mid;
        else ub = mid;
    //    printf("lb = %d  ub = %d  mid = %d
",lb,ub,mid);
    }
    return ub;
}


int main(){
    int m;
    while(scanf("%d",&m) != EOF){
        memset(c,0,sizeof(c));
        while(m--){
            int cmd;
            scanf("%d",&cmd);
            if(cmd == 0){
                int x;
                scanf("%d",&x);
                add(x,1);
            }
            if(cmd == 1){
                int x;
                scanf("%d",&x);
                if(sum(x) - sum(x-1) == 0) printf("No Elment!
");
                else add(x,-1);
            }
            if(cmd == 2){
                int x;
                scanf("%d %d",&x,&k);
                if(sum(maxn-1) - sum(x) < k) printf("Not Find!
");
                else  printf("%d
",solve(x));
            }
        }
    }
    return 0;
}