Hoax or what

Hoax or what

题意是询问一个动态序列的最小值和最大值。

可以用multiset来实现。

#include <stdio.h>
#include <set>
using namespace std;

int main() {
    freopen("h.in", "r", stdin);
    freopen("h.ans", "w", stdout);
    int n;
    while (scanf("%d", &n) && n) {
        multiset<int> bills;
        int sum = 0;
        for (int i = 0; i < n; i++) {
            int cnt;
            scanf("%d", &cnt);
            for (int j = 0; j < cnt; j++) {
                int t;
                scanf("%d", &t);
                bills.insert(t);
            }

            sum += (*bills.rbegin() - *bills.begin());

            bills.erase(bills.begin());
            bills.erase(--bills.rbegin().base());
        }
        printf("%d
", sum);
    }
}

这里给出一个最小堆的做法，通过维护一个最小堆，一个最大堆，当push元素时，将这两个元素连接到一起。当pop最大或者最小的元素时，对应删除另一个堆中对应的元素。

#include <stdio.h>
#include <algorithm>
#include <iostream> 
using namespace std;

const int MAXN = 1e6 + 5;
const int INF = 1e9;

int min_heap[MAXN], max_heap[MAXN];
int min_heap_no[MAXN], max_heap_no[MAXN];
int min_heap_no_rev[MAXN], max_heap_no_rev[MAXN];

class MinHeap {
protected:
    int count, *heap_;
public:
    MinHeap() {}
    MinHeap(int *heap) : heap_(heap), count(0) {}
    void push(int x) {
        ++count;
        heap_[count] = x;
        up(count);
    }
    int top() {
        return heap_[1];
    }
    void pop() {
        my_swap(1, count--);
        heapfy(1);
    }
    /*{{{ del(int i)*/
    void del(int i) {
        heap_[i] = -INF; up(i);
        pop();
    }
    /*}}}*/
    virtual void my_swap(int i, int j) {
        swap(heap_[i], heap_[j]);
    }
    /*{{{ heapfy(int i) */
    void heapfy(int i) {
        while (i <= count) {
            int smallest = i;
            if (2 * i <= count && heap_[2 * i] < heap_[smallest]) {
                smallest = 2 * i;
            }
            if (2 * i + 1 <= count && heap_[2 * i + 1] < heap_[smallest]) {
                smallest = 2 * i + 1;
            }
            if (i != smallest) {
                my_swap(i, smallest);
                i = smallest;
            } else {
                break;
            }
        }
    }
    /*}}}*/
    /*{{{ up(int i) */
    void up(int i) {
        while (i > 1) {
            if (heap_[i] < heap_[i / 2]) {
                my_swap(i, i / 2);
                i /= 2;
            } else {
                break;
            } 
        }
    }
    /*}}}*/
};

class MinHeapWithMap : public MinHeap {
private:
    int id, *no_, *no_rev_;
public:
    MinHeapWithMap() {}
    MinHeapWithMap(int *heap, int *no, int *no_rev) : MinHeap(heap), no_(no), no_rev_(no_rev), id(0) {}
    void push(int x) {
        no_[count + 1] = id;
        no_rev_[no_[count + 1]] = count + 1;
        id++;
        MinHeap::push(x);
    }
    virtual void my_swap(int i, int j) {
        MinHeap::my_swap(i, j);
        swap(no_[i], no_[j]);
        no_rev_[no_[i]] = i;
        no_rev_[no_[j]] = j;
    }
    int top_no() {
        return no_[1];
    }
    int no_rev(int i) {
        return no_rev_[i]; 
    }
};

class Solution {
private:
    MinHeapWithMap minHeap_, maxHeap_;
public:
    Solution() {
        minHeap_ = MinHeapWithMap(min_heap, min_heap_no, min_heap_no_rev);
        maxHeap_ = MinHeapWithMap(max_heap, max_heap_no, max_heap_no_rev);
    }
    void push(int x) {
        minHeap_.push(x);
        maxHeap_.push(-x);
    }
    int getMaxMinDiff() {
        int res = -maxHeap_.top() - minHeap_.top();
        minHeap_.del(minHeap_.no_rev(maxHeap_.top_no()));
        maxHeap_.del(maxHeap_.no_rev(minHeap_.top_no()));
        minHeap_.pop();
        maxHeap_.pop();
        return res;
    }
};

int main() {
    freopen("h.in", "r", stdin);
    freopen("h.out", "w", stdout);
    int n;
    while ( scanf("%d", &n), n) {
        Solution s;
        int sum = 0;
        for (int i = 0; i < n; i++) {
            int k;
            scanf("%d", &k);
            for (int j = 0; j < k; j++) {
                int t;
                scanf("%d", &t);
                s.push(t);
            }
            sum += s.getMaxMinDiff();
        }

        printf("%d
", sum);
    }
}