- to do
edit distance
- naive
-
if (word1[i] == word2[j]) { return rec(word1, word2, i-1, j-1);garenteed to be opted?
int rec(string& word1, string& word2, int i, int j) {
if (i<0) return j+1;
if (j<0) return i+1;
if (word1[i] == word2[j]) {
return rec(word1, word2, i-1, j-1);
} else {
return min(min(rec(word1, word2, i, j-1),
rec(word1, word2, i-1, j)),
rec(word1, word2, i-1, j-1))+1;
}
return -1; //should not reach
}
int minDistance(string word1, string word2) {
return rec(word1, word2, word1.size()-1, word2.size()-1);
}
what's wrong??
int minDistance(string word1, string word2) {
int m = word1.size(), n = word2.size(), i, j;
int dp[m+2][n+2] = {0}; //dp[i][j] holds minDistance of word1[i-1~m-1] & word2[j-1~n-1]
for (i=m; i>=0; --i) {
for (j=n; j>=0; --j) {
if (!i) {
dp[i][j] = j + dp[1][j+1];
} else if (!j) {
dp[i][j] = i + dp[i+1][1];
} else if (word1[i-1]==word2[j-1]) {
dp[i][j] = dp[i+1][j+1];
} else {
dp[i][j] = min(min(dp[i+1][j],
dp[i][j+1]),
dp[i+1][j+1])+1;
}
cout<<"dp["<<i<<"]["<<j<<"]: "<<dp[i][j]<<endl;
}
}
return dp[0][0];
}
