670. Maximum Swap LeetCode Solution

In this guide, you will get 670. Maximum Swap LeetCode Solution with the best time and space complexity. The solution to Maximum Swap problem is provided in various programming languages like C++, Java, and Python. This will be helpful for you if you are preparing for placements, hackathons, interviews, or practice purposes. The solutions provided here are very easy to follow and include detailed explanations.

Problem Statement
Complexity Analysis
Maximum Swap solution in C++
Maximum Swap solution in Java
Maximum Swap solution in Python
Additional Resources

670. Maximum Swap LeetCode Solution image

Problem Statement of Maximum Swap

You are given an integer num. You can swap two digits at most once to get the maximum valued number.
Return the maximum valued number you can get.

Example 1:

Input: num = 2736
Output: 7236
Explanation: Swap the number 2 and the number 7.

Example 2:

Input: num = 9973
Output: 9973
Explanation: No swap.

Constraints:

0 <= num <= 108

Complexity Analysis

Time Complexity: O(n)
Space Complexity: O(n)

670. Maximum Swap LeetCode Solution in C++

class Solution {
 public:
  int maximumSwap(int num) {
    string s = to_string(num);
    vector<int> lastIndex(10, -1);  // {digit: last index}

    for (int i = 0; i < s.length(); ++i)
      lastIndex[s[i] - '0'] = i;

    for (int i = 0; i < s.length(); ++i)
      for (int d = 9; d > s[i] - '0'; --d)
        if (lastIndex[d] > i) {
          swap(s[i], s[lastIndex[d]]);
          return stoi(s);
        }

    return num;
  }
};
/* code provided by PROGIEZ */

670. Maximum Swap LeetCode Solution in Java

class Solution {
  public int maximumSwap(int num) {
    char[] s = Integer.toString(num).toCharArray();
    int[] lastIndex = new int[10]; // {digit: last index}

    for (int i = 0; i < s.length; ++i)
      lastIndex[s[i] - '0'] = i;

    for (int i = 0; i < s.length; ++i)
      for (int d = 9; d > s[i] - '0'; --d)
        if (lastIndex[d] > i) {
          s[lastIndex[d]] = s[i];
          s[i] = (char) ('0' + d);
          return Integer.parseInt(new String(s));
        }

    return num;
  }
}
// code provided by PROGIEZ

670. Maximum Swap LeetCode Solution in Python

class Solution:
  def maximumSwap(self, num: int) -> int:
    s = list(str(num))
    dict = {c: i for i, c in enumerate(s)}

    for i, c in enumerate(s):
      for digit in reversed(string.digits):
        if digit <= c:
          break
        if digit in dict and dict[digit] > i:
          s[i], s[dict[digit]] = digit, s[i]
          return int(''.join(s))

    return num
 # code by PROGIEZ