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Formatted question description: https://leetcode.ca/all/2566.html

# 2566. Maximum Difference by Remapping a Digit

## Description

You are given an integer num. You know that Danny Mittal will sneakily remap one of the 10 possible digits (0 to 9) to another digit.

Return the difference between the maximum and minimum values Danny can make by remapping exactly one digit in num.

Notes:

• When Danny remaps a digit d1 to another digit d2, Danny replaces all occurrences of d1 in num with d2.
• Danny can remap a digit to itself, in which case num does not change.
• Danny can remap different digits for obtaining minimum and maximum values respectively.
• The resulting number after remapping can contain leading zeroes.
• We mentioned "Danny Mittal" to congratulate him on being in the top 10 in Weekly Contest 326.

Example 1:

Input: num = 11891
Output: 99009
Explanation:
To achieve the maximum value, Danny can remap the digit 1 to the digit 9 to yield 99899.
To achieve the minimum value, Danny can remap the digit 1 to the digit 0, yielding 890.
The difference between these two numbers is 99009.


Example 2:

Input: num = 90
Output: 99
Explanation:
The maximum value that can be returned by the function is 99 (if 0 is replaced by 9) and the minimum value that can be returned by the function is 0 (if 9 is replaced by 0).
Thus, we return 99.

Constraints:

• 1 <= num <= 108

## Solutions

Solution 1: Greedy

First, we convert the number to a string $s$.

To get the minimum value, we just need to find the first digit $s[0]$ in the string $s$, and then replace all $s[0]$ in the string with $0$.

To get the maximum value, we need to find the first digit $s[i]$ in the string $s$ that is not $9$, and then replace all $s[i]$ in the string with $9$.

Finally, return the difference between the maximum and minimum values.

The time complexity is $O(\log n)$, and the space complexity is $O(\log n)$. Where $n$ is the size of the number $num$.

• class Solution {
public int minMaxDifference(int num) {
String s = String.valueOf(num);
int mi = Integer.parseInt(s.replace(s.charAt(0), '0'));
for (char c : s.toCharArray()) {
if (c != '9') {
return Integer.parseInt(s.replace(c, '9')) - mi;
}
}
return num - mi;
}
}

• class Solution {
public:
int minMaxDifference(int num) {
string s = to_string(num);
string t = s;
char first = s[0];
for (char& c : s) {
if (c == first) {
c = '0';
}
}
int mi = stoi(s);
for (int i = 0; i < t.size(); ++i) {
if (t[i] != '9') {
char second = t[i];
for (int j = i; j < t.size(); ++j) {
if (t[j] == second) {
t[j] = '9';
}
}
return stoi(t) - mi;
}
}
return num - mi;
}
};

• class Solution:
def minMaxDifference(self, num: int) -> int:
s = str(num)
mi = int(s.replace(s[0], '0'))
for c in s:
if c != '9':
return int(s.replace(c, '9')) - mi
return num - mi


• func minMaxDifference(num int) int {
s := []byte(strconv.Itoa(num))
first := s[0]
for i := range s {
if s[i] == first {
s[i] = '0'
}
}
mi, _ := strconv.Atoi(string(s))
t := []byte(strconv.Itoa(num))
for i := range t {
if t[i] != '9' {
second := t[i]
for j := i; j < len(t); j++ {
if t[j] == second {
t[j] = '9'
}
}
mx, _ := strconv.Atoi(string(t))
return mx - mi
}
}
return num - mi
}

• function minMaxDifference(num: number): number {
const s = num + '';
const min = Number(s.replace(new RegExp(s[0], 'g'), '0'));
for (const c of s) {
if (c !== '9') {
return Number(s.replace(new RegExp(c, 'g'), '9')) - min;
}
}
return num - min;
}


• impl Solution {
pub fn min_max_difference(num: i32) -> i32 {
let s = num.to_string();
let min = s
.replace(char::from(s.as_bytes()[0]), "0")
.parse::<i32>()
.unwrap();
for &c in s.as_bytes() {
if c != b'9' {
return s.replace(c, "9").parse().unwrap() - min;
}
}
num - min
}
}