16_Maximum_69_Number.cpp

// 1323. 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.

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