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 = 300010;
// 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 = 1;
    while(T--) {
        dh.clear();
        scanf("%d%d", &n, &m);
        for(int i = 1; i <= n; i++) {
            scanf("%d", &add[i]);
        }
        int k = 1;
        for(int i = 1; i <= m; i++) {
            scanf("%d", &x);
            while(k <= x) {
                dh.insert(add[k]);
                k++;
            }
            printf("%d\n", dh.get());
        }
        printf("\n");
    }
    return 0;
}