题解 | #数字在升序数组中出现的次数#

二分查找

public class Solution {
    public int GetNumberOfK(int [] array , int k) {
        int left = 0;
        int right = array.length-1;
        int mid = 0;
        while(left < right) {
            mid = (left + right) / 2;
            if (k == array[mid]) {
                break;
            } else if (k < array[mid]) {
                right = mid - 1;
            } else {
                left = mid + 1;
            }
        }
        int i = mid;
        int count = 0;
        while (i < array.length && array[i] == k) {
            count++;
            i++;
        }
        i = mid-1;
        while(i >= 0 && array[i] == k) {
            count++;
            i--;
        }
        return count;
    }
}