Question

1432. Max Difference You Can Get From Changing an Integer

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Description

You are given an integer num. You will apply the following steps exactly two times:

• Pick a digit x (0 <= x <= 9).
• Pick another digit y (0 <= y <= 9). The digit y can be equal to x.
• Replace all the occurrences of x in the decimal representation of num by y.
• The new integer cannot have any leading zeros, also the new integer cannot be 0.

Let a and b be the results of applying the operations to num the first and second times, respectively.

Return _the max difference_ between a and b.

 

Example 1:

Input: num = 555
Output: 888
Explanation: The first time pick x = 5 and y = 9 and store the new integer in a.
The second time pick x = 5 and y = 1 and store the new integer in b.
We have now a = 999 and b = 111 and max difference = 888

Example 2:

Input: num = 9
Output: 8
Explanation: The first time pick x = 9 and y = 9 and store the new integer in a.
The second time pick x = 9 and y = 1 and store the new integer in b.
We have now a = 9 and b = 1 and max difference = 8

 

Constraints:

• 1 <= num <= 10⁸

Solutions

Solution 1

class Solution:
  def maxDiff(self, num: int) -> int:
    a, b = str(num), str(num)
    for c in a:
      if c != "9":
        a = a.replace(c, "9")
        break
    if b[0] != "1":
      b = b.replace(b[0], "1")
    else:
      for c in b[1:]:
        if c not in "01":
          b = b.replace(c, "0")
          break
    return int(a) - int(b)

class Solution {
  public int maxDiff(int num) {
    String a = String.valueOf(num);
    String b = a;
    for (int i = 0; i < a.length(); ++i) {
      if (a.charAt(i) != '9') {
        a = a.replace(a.charAt(i), '9');
        break;
      }
    }
    if (b.charAt(0) != '1') {
      b = b.replace(b.charAt(0), '1');
    } else {
      for (int i = 1; i < b.length(); ++i) {
        if (b.charAt(i) != '0' && b.charAt(i) != '1') {
          b = b.replace(b.charAt(i), '0');
          break;
        }
      }
    }
    return Integer.parseInt(a) - Integer.parseInt(b);
  }
}

class Solution {
public:
  int maxDiff(int num) {
    auto replace = [](string& s, char a, char b) {
      for (auto& c : s) {
        if (c == a) {
          c = b;
        }
      }
    };
    string a = to_string(num);
    string b = a;
    for (int i = 0; i < a.size(); ++i) {
      if (a[i] != '9') {
        replace(a, a[i], '9');
        break;
      }
    }
    if (b[0] != '1') {
      replace(b, b[0], '1');
    } else {
      for (int i = 1; i < b.size(); ++i) {
        if (b[i] != '0' && b[i] != '1') {
          replace(b, b[i], '0');
          break;
        }
      }
    }
    return stoi(a) - stoi(b);
  }
};

func maxDiff(num int) int {
  a, b := num, num
  s := strconv.Itoa(num)
  for i := range s {
    if s[i] != '9' {
      a, _ = strconv.Atoi(strings.ReplaceAll(s, string(s[i]), "9"))
      break
    }
  }
  if s[0] > '1' {
    b, _ = strconv.Atoi(strings.ReplaceAll(s, string(s[0]), "1"))
  } else {
    for i := 1; i < len(s); i++ {
      if s[i] != '0' && s[i] != '1' {
        b, _ = strconv.Atoi(strings.ReplaceAll(s, string(s[i]), "0"))
        break
      }
    }
  }
  return a - b
}