There is a strange printer with the following two special properties:
Given a string s, return the minimum number of turns the printer needed to print it.
Example 1:
Input: s = "aaabbb" Output: 2 Explanation: Print "aaa" first and then print "bbb".
Example 2:
Input: s = "aba" Output: 2 Explanation: Print "aaa" first and then print "b" from the second place of the string, which will cover the existing character 'a'.
Constraints:
1 <= s.length <= 100s consists of lowercase English letters.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.
This C solution uses a recursive function minTurns with memoization to calculate the minimum prints for a given substring. The main idea is to cover a segment and recursively calculate for the remaining parts. The dp table stores previously calculated results to optimize the performance.
C++
Java
Python
C#
JavaScript
Time Complexity: O(n^3), Space Complexity: O(n^2)
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.
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.
Time Complexity: O(n^3), Space Complexity: O(n^2). This primarily stems from recursive splitting subproblems by string breakdown.
| Approach | Complexity |
|---|---|
| Dynamic Programming with Memoization | Time Complexity: O(n^3), Space Complexity: O(n^2) |
| Greedy Segment Coverage | Time Complexity: O(n^3), Space Complexity: O(n^2). This primarily stems from recursive splitting subproblems by string breakdown. |
Strange Printer | INTUITIVE | Recursion | Memoization | NetEase | Leetcode-664 • codestorywithMIK • 15,614 views views
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