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How to Solve Minimum Cost to Make at Least One Valid Path in a Grid Problem
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Start Free for WindowsHard#1368
LeetCode ProblemMinimum Cost to Make at Least One Valid Path in a Grid
Given an m x n grid. Each cell of the grid has a sign pointing to the next cell you should visit if you are currently in this cell. The sign of grid[i][j] can be: Notice that there could be some signs on the cells of the grid that point outside the grid. You will initially start at the upper left cell (0, 0). A valid path in the grid is a path that starts from the upper left cell (0, 0) and ends at the bottom-right cell (m - 1, n - 1) following the signs on the grid. The valid path does not have to be the shortest. You can modify the sign on a cell with cost = 1. You can modify the sign on a cell one time only. Return the minimum cost to make the grid have at least one valid path.
ArrayBreadth-First SearchGraphHeap (Priority Queue)MatrixShortest Path
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Problem Breakdown
Understanding the Minimum Cost to Make at Least One Valid Path in a Grid Problem
Let's break down this LeetCode problem and understand what makes it challenging in interview settings.
Problem Statement
Given an m x n grid. Each cell of the grid has a sign pointing to the next cell you should visit if you are currently in this cell. The sign of grid[i][j] can be: Notice that there could be some signs on the cells of the grid that point outside the grid. You will initially start at the upper left cell (0, 0). A valid path in the grid is a path that starts from the upper left cell (0, 0) and ends at the bottom-right cell (m - 1, n - 1) following the signs on the grid. The valid path does not have to be the shortest. You can modify the sign on a cell with cost = 1. You can modify the sign on a cell one time only. Return the minimum cost to make the grid have at least one valid path.
HardProblem #1368
LeetCodeMinimum Cost to Make at Least One Valid Path in a Grid
Related Topics
ArrayBreadth-First SearchGraphHeap (Priority Queue)MatrixShortest Path
How Phantom Code AI Helps
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Examples
# Example 1
Input
grid = [[1,1,1,1],[2,2,2,2],[1,1,1,1],[2,2,2,2]]
Output
3
# Example 2
Input
grid = [[1,1,3],[3,2,2],[1,1,4]]
Output
0
# Example 3
Input
grid = [[1,2],[4,3]]
Output
1
Constraints
m == grid.length
n == grid[i].length
1 <= m, n <= 100
1 <= grid[i][j] <= 4
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Solve Minimum Cost to Make at Least One Valid Path in a Grid — Given an m x n grid. Each cell of the grid has a sign pointing to the next cell ...
Here's the optimal approach using Array:
def solve(input):
# Optimal O(n) solution
return result
Time: O(n) | Space: O(n)
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Frequently Asked Questions
Common questions about solving Minimum Cost to Make at Least One Valid Path in a Grid and using Phantom Code AI during coding interviews.
How does Phantom Code AI help me solve coding problems like Minimum Cost to Make at Least One Valid Path in a Grid during interviews?
Phantom Code AI generates complete solutions instantly with proper complexity analysis, letting you focus on explaining your approach and demonstrating problem-solving skills rather than getting stuck on implementation details during high-pressure situations.
What if the interviewer asks follow-up questions or modifications to problems like Minimum Cost to Make at Least One Valid Path in a Grid?
Phantom Code AI adapts in real-time. Screenshot the modified problem or use audio mode to capture the interviewer's follow-up, and get an updated solution within seconds — including edge cases and optimizations.
Can Phantom Code AI help me communicate my solution for problems like Minimum Cost to Make at Least One Valid Path in a Grid?
Yes. Phantom Code AI provides step-by-step approach explanations with 3 progressive thoughts, so you can walk through your solution naturally. It also provides time and space complexity analysis to discuss trade-offs.
How does Phantom Code AI assist with different programming languages for Minimum Cost to Make at Least One Valid Path in a Grid type problems?
Phantom Code AI supports 11 programming languages including Python, Java, C++, JavaScript, TypeScript, Go, Rust, Ruby, Swift, Kotlin, and C#. Set your preferred language and get idiomatic solutions.
What coding mistakes does Phantom Code AI help me avoid during Minimum Cost to Make at Least One Valid Path in a Grid interviews?
Phantom Code AI catches common mistakes like off-by-one errors, missing edge cases, incorrect base conditions, and suboptimal approaches. It provides clean, well-structured code that handles all edge cases.
Is Phantom Code AI detectable when solving problems like Minimum Cost to Make at Least One Valid Path in a Grid during live interviews?
No. Phantom Code AI runs as an invisible desktop overlay that doesn't appear in screen shares, recordings, or proctoring software. It works with Zoom, HackerRank, CodeSignal, CoderPad, and all major platforms.
How does Phantom Code AI help when I'm struggling with Minimum Cost to Make at Least One Valid Path in a Grid style questions under pressure?
The AI provides structured guidance: first the approach (what algorithm/data structure to use and why), then the implementation with clean code, and finally complexity analysis. This helps you think clearly even under pressure.
Does Phantom Code AI work for the coding platforms used in Minimum Cost to Make at Least One Valid Path in a Grid interviews?
Yes. Phantom Code AI works with all major coding platforms including LeetCode, HackerRank, CodeSignal, CoderPad, HackerEarth, and any browser-based coding environment.
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