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This approach constructs the string by always choosing the majority character until we need to switch to prevent three consecutive characters.
Steps:
Time Complexity: O(a + b) because each character is processed once.
Space Complexity: O(a + b) for the result string.
1using System;
2using System.Text;
3
4public class Solution {
5 public string StrWithout3a3b(int a, int b) {
6 StringBuilder sb = new StringBuilder();
7 while (a > 0 || b > 0) {
8 bool writeA = false;
9 int n = sb.Length;
10 if (n >= 2 && sb[n-1] == sb[n-2]) {
11 if (sb[n-1] == 'b') writeA = true;
12 } else {
13 if (a >= b) writeA = true;
14 }
15
16 if (writeA) {
17 sb.Append('a');
18 a--;
19 } else {
20 sb.Append('b');
21 b--;
22 }
23 }
24 return sb.ToString();
25 }
26
27 public static void Main() {
28 Solution sol = new Solution();
29 Console.WriteLine(sol.StrWithout3a3b(4, 1));
30 }
31}This C# solution uses a StringBuilder to effectively construct the output string. The logic ensures no three continuous 'a' or 'b' are appended by checking recent characters and available counts.
This approach leverages an interleaving strategy to distribute characters evenly and avoid consecutive identical sequences.
Steps:
Time Complexity: O(a + b) due to iteration through characters.
Space Complexity: O(a + b) used for the output string.
This Python solution constructs the required string using a consistent interleaving pattern that ensures no 'aaa' or 'bbb' occurs by alternating the placement of 'a's and 'b's controlled by their counts.