Edit Distance

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Problem

Given two strings, return the minimum number of single-character insertions, deletions, or substitutions required to convert one string into the other.

Examples

Example 1

Input:word1 = "horse", word2 = "ros"

Output:3

Constraints

0 <= word1.length, word2.length <= 500

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How to approach it: the 2-D Dynamic Programming pattern

The same DP idea as 1-D, but the state depends on two indices — often two positions in a grid, or a position in each of two sequences being compared.

Look for this pattern when

You're comparing two sequences (finding a longest common subsequence, edit distance).
You're computing paths or optimal values across a 2-D grid.

Read the full 2-D Dynamic Programming guide →

Video walkthroughs

Original problem on LeetCode ↗