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How to Solve Number of Ways to Form a Target String Given a Dictionary Problem
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LeetCode ProblemNumber of Ways to Form a Target String Given a Dictionary
You are given a list of strings of the same length words and a string target. Your task is to form target using the given words under the following rules: Notice that you can use multiple characters from the same string in words provided the conditions above are met. Return the number of ways to form target from words. Since the answer may be too large, return it modulo 109 + 7.
ArrayStringDynamic Programming
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Problem Breakdown
Understanding the Number of Ways to Form a Target String Given a Dictionary Problem
Let's break down this LeetCode problem and understand what makes it challenging in interview settings.
Problem Statement
You are given a list of strings of the same length words and a string target. Your task is to form target using the given words under the following rules: Notice that you can use multiple characters from the same string in words provided the conditions above are met. Return the number of ways to form target from words. Since the answer may be too large, return it modulo 109 + 7.
HardProblem #1639
LeetCodeNumber of Ways to Form a Target String Given a Dictionary
Related Topics
ArrayStringDynamic Programming
How Phantom Code Helps
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Examples
# Example 1
Input
words = ["acca","bbbb","caca"], target = "aba"
Output
6
# Example 2
Input
words = ["abba","baab"], target = "bab"
Output
4
Constraints
1 <= words.length <= 1000
1 <= words[i].length <= 1000
All strings in words have the same length.
1 <= target.length <= 1000
words[i] and target contain only lowercase English letters.
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Solve Number of Ways to Form a Target String Given a Dictionary — You are given a list of strings of the same length words and a string target. Yo...
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
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How does Phantom Code help me solve coding problems like Number of Ways to Form a Target String Given a Dictionary during interviews?
Phantom Code 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 Number of Ways to Form a Target String Given a Dictionary?
Phantom Code 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.
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Yes. Phantom Code 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 assist with different programming languages for Number of Ways to Form a Target String Given a Dictionary type problems?
Phantom Code 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 help me avoid during Number of Ways to Form a Target String Given a Dictionary interviews?
Phantom Code 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 detectable when solving problems like Number of Ways to Form a Target String Given a Dictionary during live interviews?
No. Phantom Code 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 help when I'm struggling with Number of Ways to Form a Target String Given a Dictionary 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 work for the coding platforms used in Number of Ways to Form a Target String Given a Dictionary interviews?
Yes. Phantom Code works with all major coding platforms including LeetCode, HackerRank, CodeSignal, CoderPad, HackerEarth, and any browser-based coding environment.
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