Uva-11991 - Easy Problem from Rujia Liu?

题目大意：求第k个v的编号

方法很多，这里给出比较快的，用STL中的map和vector

#include<iostream>#include<cstdio>#include<map>#include<cstring>#include<vector>using namespace std;const int N=1000005;map<int,vector<int> >ma;int n,m;int main(){    freopen("Uva.in","r",stdin);    freopen("Uva.out","w",stdout);    while((scanf("%d%d",&n,&m))==2){        ma.clear();        for(int i =1; i<=n;i++){            int x;            scanf("%d",&x);            if(!ma.count(x))ma[x]=vector<int>();//新建vector            ma[x].push_back(i);        }        for(int i = 1; i<= m; i++){            int  k,v;            scanf("%d%d",&k,&v);            if(!ma.count(v) ||ma[v].size()<k)//don't forget the second one                printf("0\n");            else printf("%d\n",ma[v][k-1]);        }    }    return 0;}