Rearrange a string so that all same characters become d distance away in python

Rearrange a string so that all same characters become d distance away in python

The problem at hand is to rearrange characters in a string so that the same characters are at least d distance apart.

Let's solve this step by step:

  1. Count the frequency of each character in the string.
  2. Place the most frequent characters at intervals of d distance.
  3. Fill in the remaining positions with other characters.

Here's a Python solution that uses a priority queue (heap) to handle this:

import heapq from collections import Counter, deque def rearrange_string(s, d): if not s: return "" # Count the frequency of each character char_count = Counter(s) # Build a max-heap based on frequency max_heap = [-((freq, char)) for char, freq in char_count.items()] heapq.heapify(max_heap) queue = deque() result = [] while max_heap: freq, char = heapq.heappop(max_heap) # Append the character to the result result.append(char) # Decrease the frequency and put it into a queue queue.append((char, freq + 1)) # If the queue size exceeds the given distance, pop an element out and push it back to max_heap if len(queue) == d: char, freq = queue.popleft() if freq: heapq.heappush(max_heap, (freq, char)) # If the result size is equal to the input string, return the result, otherwise, it's not possible return ''.join(result) if len(result) == len(s) else "" # Test s = "aaabbcc" d = 2 print(rearrange_string(s, d)) # Example Output: "abacbac" or similar valid string

This solution will return a rearranged string if it's possible to do so. Otherwise, it will return an empty string, indicating it's not possible to rearrange the string with the given distance d.

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