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

        for(int i=1; i<=n; i++){
            for(int j=1; j<=m; j++){
                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], dp[i-1][j-1]});
            }
        }
        return dp[n][m];
    }
};