leetcode 72 - Edit Distance

https://leetcode.com/problems/edit-distance/

Given two strings word1 and word2, return the minimum number of operations required to convert word1 to word2.

You have the following three operations permitted on a word:

Insert a character
Delete a character
Replace a character

Example 1:

Input: word1 = “horse”, word2 = “ros”
Output: 3
Explanation:
horse -> rorse (replace ‘h’ with ‘r’)
rorse -> rose (remove ‘r’)
rose -> ros (remove ‘e’)
Example 2:

Input: word1 = “intention”, word2 = “execution”
Output: 5
Explanation:
intention -> inention (remove ‘t’)
inention -> enention (replace ‘i’ with ‘e’)
enention -> exention (replace ‘n’ with ‘x’)
exention -> exection (replace ‘n’ with ‘c’)
exection -> execution (insert ‘u’)

Constraints:

0 <= word1.length, word2.length <= 500
word1 and word2 consist of lowercase English letters.

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class Solution {
public:
int minDistance(string word1, string word2) {
int size1 = word1.size();
int size2 = word2.size();

int memo[size1+1][size2+1];

for (int len = 0; len <= size1; len++)
memo[len][0] = len;
for (int len = 0; len <= size2; len++)
memo[0][len] = len;

for (int i = 1; i <= size1; i++) {
for (int j = 1; j <= size2; j++) {
memo[i][j] = min(memo[i-1][j], memo[i][j-1]) + 1;

if (word1[i-1] == word2[j-1])
memo[i][j] = min(memo[i-1][j-1], memo[i][j]);
else
memo[i][j] = min(memo[i-1][j-1] + 1, memo[i][j]);
}
}

return memo[size1][size2];
}
};