583

class Solution {
public:
    int minDistance(string word1, string word2) {
        int n = word1.length(), m = word2.length();
        int dp[n+1][m+1];
        memset(dp, 0, sizeof dp);

        for(int i=0; i<=n; i++)
            for(int j=0; j<=m; j++){
                if(i*j == 0)
                    dp[i][j] = i+j;
                else if(word1[i-1] == word2[j-1])
                    dp[i][j] = dp[i-1][j-1];
                else
                    dp[i][j] = 1 + min(dp[i-1][j], dp[i][j-1]);
            }
        return dp[n][m];
    }
};