LeetCode 072 Edit Distance

int minDistance(string word1, string word2) {
int len1 = word1.length();
int len2 = word2.length();
vector<vector<int>> f(len1 + 1, vector<int>(len2 + 1));

for(int i = 0 ; i <= len1 ; i++)
f[i][0] = i;
for(int j = 0 ; j <= len2 ; j++)
f[0][j] = j;

for(int i = 1 ; i <= len1 ; i++) {
for(int j = 1 ; j <= len2 ; j++) {
if(word1[i - 1] == word2[j - 1]) {
f[i][j] = min(f[i - 1][j - 1], min(f[i-1][j], f[i][j - 1]) + 1);
}
else {
f[i][j] = min(f[i - 1][j - 1] + 1, min(f[i-1][j], f[i][j - 1]) + 1);
}
}
}
return f[len1][len2];
}