题解 | #找出特定体重的牛群#

题目考察的知识点: 二分查找

题目解答方法的文字分析:

二分查找左右边界即可

本题解析所用的编程语言:Java

完整且正确的编程代码

import java.util.*;


public class Solution {
    /**
     * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
     *
     *
     * @param weights int整型一维数组
     * @param target int整型
     * @return int整型一维数组
     */
    public int[] searchRange (int[] weights, int target) {
        // write code here
        int length = weights.length;
        if(length == 0) return new int[] {-1, -1};
        int left = 0, right = length - 1;
        int l,r;
        while (left < right) {
            int mid = (left + right) / 2;
            if (weights[mid] <= target) {
                right = mid;
            } else {
                left = mid + 1;
            }
        }
        if (left == -1) {
            return new int[] {-1, -1};
        }
        l = weights[left] == target ? left : -1;
        left = 0;
        right = length - 1;
        while (left < right) {
            int mid = (left + right + 1) / 2;
            if (weights[mid] < target) {
                right = mid - 1;
            } else {
                left = mid;
            }
        }
        r = weights[left] == target ? left : -1;
        return new int[] {l, r};
    }

}