【LeetCode】Search for a Range

public class Solution {
    public int binarySearchFirst(int[] A, int target){
        int l = 0, h = A.length - 1;
        int p = -1;
        while(l <= h){
            int mid = l + ((h - l) >> 1);
            if(target <= A[mid]){//注意这个等号，尽量要往小的方向走
                h = mid - 1;
                if(A[mid] == target &&(p == -1 || p > mid )){
                    p = mid;//记录需要输出的值，如果有多个相等的，取小的。
                }
            }
            else {
                l = mid + 1;
            }
        }
        return p;
    }
    public int binarySearchLast(int[] A, int target){
        int l = 0, h = A.length - 1;
        int p = -1;
        while(l <= h){
            int mid = l + ((h - l) >> 1);
            if(target >= A[mid]){//往大的方向走
                l = mid + 1;
                if(A[mid] == target && p < mid){
                    p = mid;
                }
            }
            else{
                h = mid - 1;
            }
        }
        return p;
    }
    
    public int[] searchRange(int[] A, int target) {
        int[] ans = new int[2];
        ans[0] = binarySearchFirst(A, target);
        ans[1] = binarySearchLast(A, target);
        return ans;
        
    }
}