堆

今天刚刚学习堆和堆排，先手抄了一遍算法书，再自己实现一遍，作为巩固。

update : 早上起床把小根堆写了一遍 = 。 = 

/*  小根堆  */
#include <iostream>
#include <vector>
using namespace std;
void downAdjust(int to_adjust,int bound,vector<int> & heap){
    int i = to_adjust, j = i * 2;
    while(j <= bound){
        if(j + 1 <= bound and heap[j] > heap[j+1]){
            j = j + 1;
        }
        if(heap[i] > heap[j]){
            swap(heap[i], heap[j]);
            i = j;
            j = i*2;
        }else break;
    }
}
void upAdjust(int to_adjust,vector<int> & heap){
    int i = to_adjust, j = i/2;
    while(j >= 1){
        if(heap[i] < heap[j]){
            swap(heap[i], heap[j]);
            i = j;
            j = i/2;
        }else break;
    }
}
void insert(int v,vector<int> & heap){
    heap.push_back(v);
    int s = (int)heap.size()-1;
    upAdjust(s, heap);
}
void pop(vector<int>& heap){
    swap(heap[1], heap.back());
    heap.pop_back();
    int s = (int)heap.size() - 1;
    downAdjust(1,s,heap);
}
void create_heap(vector<int>&heap){
    int s = (int)heap.size()-1;
    for(int i = s/2; i >= 1; i--){
        downAdjust(i, s, heap);
    }
}
void heapSort(vector<int>& heap){
    create_heap(heap);
    for(int s = (int)heap.size()-1; s > 1; s--){
        swap(heap[1], heap[s]);
        downAdjust(1,s-1, heap);
    }
}
int main(){
    vector<int> test = {-1,2,4,1,5,23,56,75,32,134,5435,31,1,3412,45,9};
    heapSort(test);
    for(vector<int>::iterator it = test.begin(); it not_eq test.end(); it++)cout<<*it<<" ";
    return 0;
}

- - - - - - - - - - - - - - -- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

/*    大根堆    */
#include <iostream>
#include <vector>
#define Maxsize    1000 + 1
using namespace std;
void downAdjust(int low,int high,vector<int>& Heap){
    int i = low, j = i * 2; //  i 是将要下调的结点 , j 是i的左结点
    while( j <= high ){ // 存在孩子结点
        if(j + 1 <= high and Heap[j] < Heap[j+1]){
            j = j + 1;
        }
        if(Heap[i] < Heap[j]){
            swap(Heap[i],Heap[j]);
            i = j;
            j = i*2;
        }else break;
    }
}
void creatHeap(vector<int>& Heap){
    int s = (int)Heap.size() - 1;
    for(int i = s/2; i >= 1; i--){
        downAdjust(i, s, Heap);
        // 不需要考虑最底层的结点, 直接从次底层开始,从下向上遍历调整。
        // 为什么不从堆顶向下调整呢？
        //如果从堆顶调整, 对于一个结点,在调整其子结点的步骤中可能会破坏该节点的局部大根堆结构,导致建立堆错误。
    }
}
void pop(vector<int>& Heap){
    int s = (int)Heap.size() - 1;
    swap(Heap[1], Heap[s]);
    Heap.pop_back();
    downAdjust(1, s-1, Heap);
}
void upAdjust(int high,vector<int>& Heap){
    int i = high, j = high/2;
    while( j >= 1){
        if(Heap[i] > Heap[j]){
            swap(Heap[i], Heap[j]);
            i = j;
            j = i/2;
        }else break;
    }
}
void insert(vector<int>&Heap,int value){
    Heap.push_back(value);
    int s = (int)Heap.size() - 1;
    upAdjust(s, Heap);
}
void HeapSort(vector<int>& Heap){
    creatHeap(Heap);
    for(int s = (int)Heap.size() - 1; s > 1; s--){
        swap(Heap[1], Heap[s]);
        downAdjust(1, s-1, Heap);
    }
}
int main(){
    vector<int> test = {0,1,314,41,2,1,3,14,14,3,11313,134}; // 0 是占位符
    HeapSort(test);
    for(vector<int> :: iterator it = test.begin() + 1; it not_eq test.end(); it++)cout<<*it<<" ";
    return 0;
}