堆

最近在自学数据结构，写了个最大堆模板，heap的大小到时候用malloc动态申请

int heapsize, *heap;

void up(int x){//自下而上调整堆 

    while(x != 1){

        if(heap[x>>1] < heap[x]){

            swap(heap[x>>1], heap[x]);

            x >>= 1;

        }

        else break;

    }

} 

void down(int x){//自上而下调整堆 

    int y = x<<1;

    while(y <= heapsize){

        if(y < heapsize && heap[y] < heap[y+1])

            y++;

        if(heap[y] > heap[x]){

            swap(heap[y], heap[x]);

            x = y, y = x<<1;

        }    

        else break;

    }

}

void pop(){//取出堆顶元素 

    heap[1] = heap[heapsize--];

    down(1);

}

void push(int x){//增加新元素

    heap[++heapsize] = x;

    up(heapsize);

}

void build(){//建立堆 

    for(int i = 1; i <= heapsize; i++) up(i);

}

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