zoj 3635 Cinema in Akiba（树状数组+二分）

用树状数组维护第i个位置前面有多少空位，然后二分查询。

代码：

#include <iostream>#include <cstdio>#include <cstring>#define maxn 50010using namespace std;int a[maxn];int c[maxn];int N;int res[maxn];int lowbit(int n){return n&(-n);}void add(int p,int n){while(p<=N){c[p]+=n;p+=lowbit(p);}}int sum(int p){    int res=0;    while(p>0){res+=c[p];p-=lowbit(p);    }    return res;}int solve(int k){    int l=0,r=N+1;    int m;while(l<r-1){m=(l+r)>>1;if(sum(m)>=k) r=m;else l=m;}return r;}int main(){    while(~scanf("%d",&N)){memset(a,0,sizeof(a));memset(c,0,sizeof(c));for(int i=1;i<=N;i++){scanf("%d",&a[i]);add(i,1);}for(int i=1;i<=N;i++){res[i]=solve(a[i]);add(res[i],-1);}int m;scanf("%d",&m);for(int i=1;i<=m;i++){int t;scanf("%d",&t);printf("%d",res[t]);if(i<m){printf(" ");}else printf("\n");}    }    return 0;}