题解 | #数字在升序数组中出现的次数# | C++

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 GetNumberOfK(vector<int>& nums, int k) {
        int pos = -1;
        int l = 0, r = nums.size() - 1;
        while (l <= r) {
            int mid = l + (r - l);
            if (nums[mid] == k) {
                pos = mid;
                break;
            } else if (nums[mid] > k) {
                r = mid - 1;
            } else {
                l = mid + 1;
            }
        }
        if (pos == -1) return 0;
        int cnt = 1;
        r = pos+1;
        l = pos-1;
        while (r < nums.size()) {
            if (nums[r] == k) cnt++;
            else break;
            r++;
        }
        while (l >= 0) {
            if (nums[l] == k) cnt++;
            else break;
            l--;
        }
        return cnt;
    }
};