poj1442 Black Box

The Black Case 好啊！

首先，读题很艰难...

读完题，发现是求第k小的数，那么我们用splay水过对顶堆水过即可。

 #include <cstdio>
 #include <queue>
 const int N = ;
 // poj 1442 黑箱
 struct DeHeap {
     std::priority_queue<int> DOWN;
     std::priority_queue<int, std::vector<int>, std::greater<int> > UP;
     inline void clear() {
         while(!UP.empty()) {
             UP.pop();
         }
         while(!DOWN.empty()) {
             DOWN.pop();
         }
         return;
     }
     inline void insert(int x) {
         if(DOWN.empty()) {
             UP.push(x);
         }
         else if(x >= DOWN.top()) {
             UP.push(x);
         }
         else {
             DOWN.push(x);
             UP.push(DOWN.top());
             DOWN.pop();
         }
         return;
     }
     inline int get() {
         int x = UP.top();
         DOWN.push(x);
         UP.pop();
         return x;
     }
 }dh;

 int add[N];

 int main() {
     int n, m, x, T = ;
     while(T--) {
         dh.clear();
         scanf("%d%d", &n, &m);
         for(int i = ; i <= n; i++) {
             scanf("%d", &add[i]);
         }
         int k = ;
         for(int i = ; i <= m; i++) {
             scanf("%d", &x);
             while(k <= x) {
                 dh.insert(add[k]);
                 k++;
             }
             printf("%d\n", dh.get());
         }
         printf("\n");
     }
     return ;
 }

AC代码