二分查找模板和详细练习题

Posted 2022-11-20 Mr_渣渣辉

二分查找练习题：
查找
二分查找
Doubles
Pie
Can you solve this equation?
Can you find it？
Wildcard
4 Values whose Sum is 0
Median

二分查找基础模板

int binarySearch(int a[],int ans,int length)
    int left = 1 , right = length - 1;
    while(left <= right)
        int middle = left + (right - left) / 2;
        if(a[middle] == ans)
            return middle;
        else if(a[middle]>ans)
            right = middle - 1;
        else
            left = middle + 1;
        
    
    return -1;

左边界二分模板

int binarySearch(int a[],int ans,int length)
    int left = 1 , right = length ;
    while(left < right)
        int middle = left + (right - left) / 2;
        if(a[middle] == ans)
            right = middle;
        else if(a[middle]>ans)
            right = middle ;
        else
            left = middle + 1;
        
    
    return a[left] == ans ? left : -1;

右边界二分模板

int binarySearch(int a[],int ans,int length)
    int left = 1 , right = length+1 ;
    while(left < right)
        int middle = left + (right - left) / 2;
        if(a[middle] == ans)
            left = middle + 1;
        else if(a[middle]>ans)
            right = middle ;
        else
            left = middle + 1;
        
    
    return a[left -1] == ans ? left - 1 : -1;