統計一個數字在排序數組中出現的次數。

示例 1:

輸入: nums = [5,7,7,8,8,10], target = 8
輸出: 2
示例 2:

輸入: nums = [5,7,7,8,8,10], target = 6
輸出: 0

限制：

0 <= 數組長度 <= 50000

解題思路

1. 先用二分法查找出其中一個目標元素
2. 再向目標元素兩邊查找目標元素

代碼

class Solution {public int search(int[] nums, int target) {int l = 0, r = nums.length - 1;while (l <= r) {int mid = (r - l) / 2 + l;if (nums[mid] == target) {int left = mid-1, right = mid+1;while (left >= 0 && nums[left] == target)left--;while (right < nums.length && nums[right] == target)right++;return right - left - 1;} else if (nums[mid] > target)r = mid - 1;else l = mid + 1;}return 0;}
}