Leetcode 704. Binary search

difficulty ： Easy to
frequency ：99
subject ： Given a n The elements are ordered （ Ascending ） integer array nums And a target value target , Write a function search nums Medium target, If the target value has a return subscript , Otherwise return to -1.

Ideas : Just look in two

Be careful ：

• while Inside is l<=r;
• And then on the left , On the left ==>r=mid-1
• If it's on the right , On the right side ==>l=mid+1
• int In the array length Attribute , and String Inside length Is the method

class Solution {
    
    public int search(int[] nums, int target) {
    
        int len=nums.length;
        int l=0;
        int r=len-1;
        while(l<=r){
    
            int mid=(r+l)/2;
            if(target==nums[mid]){
    
                return mid;
            }
            if(target<=nums[mid]){
    
                r=mid-1;
            }
            else{
    
                l=mid+1;
            }
        }
        return -1;
    }
}