Binary search method (binary search algorithm)

Binary search (binary search algorithm)

Binary search is also called binary search. The
core idea: control the search range, each time you find or exclude half of the last search data.
Steps:
  1. First find the middle value mid of the interval
  2. Compare the middle value mid with the value x If the required number x is smaller than mid, take the interval to the left of mid to continue binary search; if the required number x is greater than mid, take the interval to the right of mid to continue binary search; if the required value x=mid returns mid ;

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Example
Use binary search to find a random value in an array of 0-9 and output

#include<stdio.h>
#include<stdlib.h>
#include<time.h>
int main()
{
    
    
	int a[] = {
    
     0, 1, 2, 3, 4, 5, 6, 7, 8, 9 };
	srand((unsigned int)time(0));
	int x = rand() % 10;
	printf("x:%d\n",x);
	int left = 0;
	int right = 9;
	while (left <= right)
	{
    
    
		int mid = (left + right) / 2;     //取mid左右区间的中点
		if (x < mid)                     //如果要求的数比mid小就取mid左边的区间
		{
    
    
			right = mid - 1;             //因为上面已经比较过x和mid；所以不用再比较mid取mid-1为右端点
		}
		else if (x > mid)                //如果要求的数比mid大就取mid右边的区间
		{
    
    
			left = mid + 1;              //因为上面已经比较过x和mid；所以不用再比较mid取mid+1为左端点
		}
		else
		{
    
    
			printf("找到了:%d\n",mid);
			return mid;                  //如果mid=x直接返回mid
		}
	}
	printf("没找到\n");
	return 0;
}

Note : The data for binary search needs to be sorted first