Skip to content

2375. Construct Smallest Number From DI String 👍

  • Time: $O(n)$
  • Space: $O(n)$
 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
class Solution {
 public:
  string smallestNumber(string pattern) {
    string ans;
    stack<char> stack{{'1'}};

    for (const char c : pattern) {
      char maxSorFar = stack.top();
      if (c == 'I')
        while (!stack.empty()) {
          maxSorFar = max(maxSorFar, stack.top());
          ans += stack.top(), stack.pop();
        }
      stack.push(maxSorFar + 1);
    }

    while (!stack.empty())
      ans += stack.top(), stack.pop();

    return ans;
  }
};

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
class Solution {
  public String smallestNumber(String pattern) {
    StringBuilder sb = new StringBuilder();
    Deque<Character> stack = new ArrayDeque<>(Arrays.asList('1'));

    for (final char c : pattern.toCharArray()) {
      char maxSorFar = stack.peek();
      if (c == 'I')
        while (!stack.isEmpty()) {
          maxSorFar = (char) Math.max(maxSorFar, stack.peek());
          sb.append(stack.pop());
        }
      stack.push((char) (maxSorFar + 1));
    }

    while (!stack.isEmpty())
      sb.append(stack.pop());

    return sb.toString();
  }
}

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
class Solution:
  def smallestNumber(self, pattern: str) -> str:
    ans = []
    stack = ['1']

    for c in pattern:
      maxSorFar = stack[-1]
      if c == 'I':
        while stack:
          maxSorFar = max(maxSorFar, stack[-1])
          ans.append(stack.pop())
      stack.append(chr(ord(maxSorFar) + 1))

    while stack:
      ans.append(stack.pop())

    return ''.join(ans)