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This approach involves using dynamic programming with memoization to find the minimum number of turns needed to print the string. The idea is to define a recursive function that prints a substring from index i to index j, using memoization to avoid unnecessary repeated calculations.
Time Complexity: O(n^3), Space Complexity: O(n^2)
1#include <iostream>
2#include <vector>
3using namespace std;
4
5class Solution {
6public:
7 static int strangePrinter(string s) {
8 int n = s.size();
9 vector<vector<int>> dp(n, vector<int>(n, 0));
10 for (int len = 1; len <= n; ++len) {
11 for (int i = 0; i + len <= n; ++i) {
12 int j = i + len - 1;
13 dp[i][j] = (i == j) ? 1 : dp[i + 1][j] + 1;
14 for (int k = i + 1; k <= j; ++k) {
15 if (s[k] == s[i]) {
16 dp[i][j] = min(dp[i][j], dp[i][k - 1] + (k + 1 <= j ? dp[k + 1][j] : 0));
17 }
18 }
19 }
20 }
21 return dp[0][n - 1];
22 }
23};
24
25int main() {
26 Solution solution;
27 string s = "aba";
28 cout << solution.strangePrinter(s) << endl;
29 return 0;
30}This C++ implementation uses dynamic programming to fill a 2D dp array where dp[i][j] represents the minimum turns needed to print the substring from i to j. It iteratively grows the length of the substring and calculates the minimal operations while comparing characters to find new segments covered in minimum turns.
This approach uses a greedy strategy to minimize the number of character segments that need to be printed. Instead of forming a full dp matrix, it strategizes the printing operations based on visible segments of similar characters, exploiting shared coverage.
Time Complexity: O(n^3), Space Complexity: O(n^2). This primarily stems from recursive splitting subproblems by string breakdown.
1class Solution:
2 def strangePrinter(self, s: str) ->
This optimized greedy Python solution leverages a streamlined version of the string by compressing repeated characters. It utilizes memoization within a divided recursive structure. Segments are collapsed as the helper ranges over valid substrings, aiming for spaced repetition minimization.