题目描述

统计一个数字在排序数组中出现的次数。

利用map建立映射关系, 做题以来思路最快, 变的最快, 提交一次过

class Solution {public:    int GetNumberOfK(vector
    
      data ,int k) {        map
     
       myMap;                for (int i = 0; i < data.size(); i++) {            myMap[data[i]]++;        }                return myMap[k];    }};
     
    

class Solution {public:    int GetNumberOfK(vector
    
      data ,int k) {        if (data.empty()) return 0;                int count = 0;        int low = 0;        int high = data.size() - 1;                while (true) {            int mid = (low + high) / 2;            if (data[mid] == k) {                int temp = mid;                while ((temp <= high) && (data[temp] == k)) {                    count++;                    temp++;                }                temp = mid;                while ((temp >= 0) && (data[temp] == k)) {                    count++;                    temp--;                }                return count-1;            }            else if (low > high) {                return 0;            }            else {                if (data[mid] > k) {                    high = mid - 1;                }                else {                    low = mid + 1;                }            }        }    }};