含有重复元素的二分查找

查找最左边的那个target元素

public int binarySearch(int []nums,int start,int end , int target){
    int l = start , r = end , m = 0;
    while(l <= r){
        m = l+(r-l)/2;
        if(nums[m] >= target){
            r = m - 1;
        }else{
            l = m + 1;
        }
    }
    return l<nums.length && nums[l] == target?l:-1;
}

查找最右边的那个target元素

public int binarySearch(int []nums,int start,int end , int target){
    int l = start , r = end , m = 0;
    while(l <= r){
        m = l+(r-l)/2;
        if(nums[m] <= target){
            l = m + 1;
        }else{
            r = m - 1;
        }
    }
    return r>=0 && nums[r] == target?r:-1;
}

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