题解 | #数字在升序数组中出现的次数#

class Solution {
public:
    /**
     * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
     *
     * 
     * @param nums int整型vector 
     * @param k int整型 
     * @return int整型
     */

    int GetNumberIndex(vector<int>& nums, int k) {
        int mid = 0;
        int left = 0;
        int right = nums.size() - 1;
        while (left <= right) {
           mid = (left + right) / 2;
           if (nums[mid] == k) {
                return mid;
           }else if(k > nums[mid]){
                left = mid + 1;
           }else {
                right = mid -1;
           }
        }

        return  -1;
    }
    int GetNumberOfK(vector<int>& nums, int k) {
       int index = GetNumberIndex(nums,k);
       if(index == -1)
       {
            return 0;
       }

       int icount = 1;
       for(int i = index - 1;i>=0;i--)
       {
            if (nums[i] == k) {
                icount++;
            }else {
                break;
            }
       }

        for(int i = index + 1;i<nums.size();i++)
       {
            if (nums[i] == k) {
                icount++;
            }else {
                break;
            }
       }
       return icount;
    }
};