CS-Notes/docs/notes/53. 数字在排序数组中出现的次数.md

53. 数字在排序数组中出现的次数

NowCoder

题目描述

Input:
nums = 1, 2, 3, 3, 3, 3, 4, 6
K = 3

Output:
4

解题思路

public int GetNumberOfK(int[] nums, int K) {
    int first = binarySearch(nums, K);
    int last = binarySearch(nums, K + 1);
    return (first == nums.length || nums[first] != K) ? 0 : last - first;
}

private int binarySearch(int[] nums, int K) {
    int l = 0, h = nums.length;
    while (l < h) {
        int m = l + (h - l) / 2;
        if (nums[m] >= K)
            h = m;
        else
            l = m + 1;
    }
    return l;
}