Today I have done leetcode's November LeetCoding Challenge with cpp.

November LeetCoding Challenge 7

Description

Maximum 69 Number

You are given a positive integer num consisting only of digits 6 and 9.

Return the maximum number you can get by changing at most one digit (6 becomes 9, and 9 becomes 6).

Example 1:

Input: num = 9669
Output: 9969
Explanation: 
Changing the first digit results in 6669.
Changing the second digit results in 9969.
Changing the third digit results in 9699.
Changing the fourth digit results in 9666.
The maximum number is 9969.

Example 2:

Input: num = 9996
Output: 9999
Explanation: Changing the last digit 6 to 9 results in the maximum number.

Example 3:

Input: num = 9999
Output: 9999
Explanation: It is better not to apply any change.

Constraints:

• 1 <= num <= 104
• num consists of only 6 and 9 digits.

Solution

class Solution {
public:
  int maximum69Number (int num) {
    auto s = to_string(num);
    for(auto &c : s) {
      if(c == '6') {
        c = '9';
        break;
      }
    }
    return stoi(s);
  }
};

// Accepted
// 153/153 cases passed (7 ms)
// Your runtime beats 9.01 % of cpp submissions
// Your memory usage beats 45.85 % of cpp submissions (6 MB)