0072-edit-distance.cpp

class Solution {
public:
    
    int f(string word1, string word2,int i,int j,vector<vector<int>>&dp){
        if(i<0) return j+1;
        if(j<0) return i+1;
        if(dp[i][j]!=-1) return dp[i][j];
        if(word1[i]==word2[j]){
            return dp[i][j] = 0 + f(word1,word2,i-1,j-1,dp); 
        }
        return dp[i][j] = 1 + min(f(word1,word2,i-1,j,dp),min(f(word1,word2,i-1,j-1,dp),f(word1,word2,i,j-1,dp)));
    }
    
    
    int minDistance(string word1, string word2) {
        int n= word1.size();
        int m = word2.size();
        vector<vector<int>>dp(word1.size()+1,vector<int>(word2.size()+1,-1));
        for(int i=0;i<=n;i++){
            dp[i][0]=i;
        }
        for(int j=0;j<=m;j++){
            dp[0][j]=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] = 0 + dp[i-1][j-1]; 
        }
        else
        dp[i][j] = 1 + min(dp[i-1][j],min(dp[i-1][j-1],dp[i][j-1]));  
            }
        }
        return dp[n][m];
    }
};