笔记1-排序

排序算法：
#include <iostream>

//冒泡排序
void bubbleSort(int array[],int size){
    
    std::cout << "array= " << array << std::endl;
    
    for (int end = size-1; end > 0; end--) {
        
        for (int begin = 1; begin <= end; begin++) {
            
            if (array[begin] < array[begin-1]) {
                
                int tmp = array[begin];
                
                array[begin] = array[begin-1];
                
                array[begin-1] = tmp;
                
            }
        }
    }
    
    for(int i = 0; i < size; ++i)
    {
        printf("%d ", array[i]);
    }
}

//优化1(如果序列已经完全有序，可以提前终止冒泡排序)
void bubbleSort1(int array[],int size){
    
    std::cout << "array= " << array << std::endl;
    
    for (int end = size-1; end > 0; end--) {
        
        bool sorted = true;
        
        for (int begin = 1; begin <= end; begin++) {
            
            if (array[begin] < array[begin-1]) {
                
                int tmp = array[begin];
                
                array[begin] = array[begin-1];
                
                array[begin-1] = tmp;
                
                sorted = false;
                
            }
        }
        
        if (sorted == true) {
            
            break;
            
        }
    }
    
    for(int i = 0; i < size; ++i)
    {
        printf("%d ", array[i]);
    }
}

//优化2(如果序列尾部已经局部有序，可以记录最后1次交换的位置，减少比较次数)
void bubbleSort3(int array[],int size){
    
    std::cout << "array= " << array << std::endl;
    
    for (int end = size-1; end > 0; end--) {
        
        int sortedIndex = 1;
        
        for (int begin = 1; begin <= end; begin++) {
            
            if (array[begin] < array[begin-1]) {
                
                int tmp = array[begin];
                
                array[begin] = array[begin-1];
                
                array[begin-1] = tmp;
                
                sortedIndex = begin;
                
            }
        }
        
        end = sortedIndex;
    }
    
    for(int i = 0; i < size; ++i)
    {
        printf("%d ", array[i]);
    }
}

//选择排序
void selectionSort(int array[],int size){
    
    for (int end = size-1; end > 0; end--) {
        
        int maxIndex = 0;
        
        for (int begin = 1; begin <= end; begin++) {
            
            if (array[maxIndex] < array[begin]) {//假定的这个数小于循环扫描的数
                
                maxIndex = begin;
                
            }
        }
        int tmp = array[maxIndex];
        
        array[maxIndex] = array[end];
        
        array[end] = tmp;
        
    }
    
    for(int i = 0; i < size; ++i)
    {
        printf("%d ", array[i]);
    }
}