一、题目内容

二、题解

解法1：

思路

二分法，找到目标值后判定，继续向左还是向右

代码

public class Solution {
    public static int findLen(int[] nums, int target) {
        if (nums == null || nums.length == 0) {
            return 0;
        }
        int left = find(nums, target, true);
        int right = find(nums, target, false);
        return right - left;
    }
    private static int find(int[] nums, int target, boolean leftFlag) {
        int left = 0, right = nums.length - 1;
        while (left < right) {
            int mid = (right + left) / 2;
            if (nums[mid] < target) {
                left = mid + 1;
            } else if (nums[mid] > target) {
                right = mid - 1;
            } else {
                //求左还是求右
                if (leftFlag) {
                    right = mid - 1;
                } else {
                    left = mid + 1;
                }
            }
        }
        return left;
    }
}