题意：给你一个数组，求第k个v的下标是
思路：用map和vector结合，很巧妙的应用，节省了很大的空间
#include #include #include #include #include #include using namespace std; map > a; int main(){ int n,m,x,y; while (scanf("%d%d",&n,&m) != EOF){ a.clear(); for (int i = 0; i < n; i++){ scanf("%d",&x); if (!a.count(x)) a[x] = vector (); a[x].push_back(i+1); } while (m--){ scanf("%d%d",&x,&y); if (!a.count(y) || a[y].size() < x) printf("0\n"); else printf("%d\n",a[y][x-1]); } } return 0; }