1881. Maximum Value after Insertion.cpp

You are given a very large integer n, represented as a string,?????? and an integer digit x. The digits in n and the digit x are in the inclusive range [1, 9], and n may represent a negative number.

You want to maximize n's numerical value by inserting x anywhere in the decimal representation of n??????. You cannot insert x to the left of the negative sign.

For example, if n = 73 and x = 6, it would be best to insert it between 7 and 3, making n = 763.
If n = -55 and x = 2, it would be best to insert it before the first 5, making n = -255.
Return a string representing the maximum value of n?????? after the insertion.

 

Example 1:

Input: n = "99", x = 9
Output: "999"
Explanation: The result is the same regardless of where you insert 9.
Example 2:

Input: n = "-13", x = 2
Output: "-123"
Explanation: You can make n one of {-213, -123, -132}, and the largest of those three is -123.
 

Constraints:

1 <= n.length <= 105
1 <= x <= 9
The digits in n??? are in the range [1, 9].
n is a valid representation of an integer.
In the case of a negative n,?????? it will begin with '-'.






class Solution {
public:
    string maxValue(string s, int x) {
        int n = s.length();
        string res = "";
        
        if (s[0] == '-') {
            char cx = x + '0';
            
            for (int i = 1; i < n; i++) {
                if (cx < s[i]) {
                    res = s.substr(0, i) + cx + s.substr(i, n);
                    break;
                }
            }
            if (res.size() == 0) res = s + cx;
            
        } else {
            char cx = x + '0';
            
            for (int i = 0; i < n; i++) {
                if (cx > s[i]) {
                    res = s.substr(0, i) + cx + s.substr(i, n);
                    break;
                }
            }
            if (res.size() == 0) res = s + cx;
        }
        
        return res;
    }
};