剑指 Offer 53 - I. 在排序数组中查找数字 I 题解

 

二分法找到目标 左右寻找。直接拿下！！！

class Solution {
    public int search(int[] nums, int target) {
//二分法 查找
    if(nums==null || nums.length==0){
        return 0;
    }
   return binarySearch(nums,target,0,nums.length-1);
    }
    public int binarySearch(int[] nums,int target,int left,int right){
        int mid = (left+right)/2;
        int temp=0;
        
        int count=0;
        if(nums[mid]==target){
            temp=mid;
            while(temp>=left && nums[temp]==target){
                count++;
                temp--;
            }
            temp=mid+1;
             while(temp<=right && nums[temp]==target){
                count++;
                temp++;
            }
            return count;
        }
        if(nums[mid]<target && right>mid){
           return binarySearch(nums,target,mid+1,right);
        }
       if(nums[mid]>target && mid>left){
          return  binarySearch(nums,target,left,mid);
        }
        return 0;
    }
}