```
class Solution {
public:
int minDistance(string word1, string word2) {
int m=word1.size(),n=word2.size();
//最长公共 LCS
vector<vector<int>> dp(m+1,vector<int>(n+1,0));
for(int i=1;i<=m;i++){
for(int j=1;j<=n;j++){
if(word1[i-1]==word2[j-1])dp[i][j]=dp[i-1][j-1]+1;
else dp[i][j]=max(dp[i-1][j],dp[i][j-1]);
}
}//end for
return m+n - 2*dp[m][n];
}
};
```