Question

统计一个数字在排序数组中出现的次数。

思路：二分查找。找到该数的最左位置。

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