LeetCode: Edit Distance

知道是dp，没弄出状态方程。。

class Solution {
public:
    int minDistance(string word1, string word2) {
        // Start typing your C/C++ solution below
        // DO NOT write int main() function
        vector<vector<int>> f(word1.size()+1, vector<int>(word2.size()+1));
        for (int i = 0; i <= word1.size(); i++) f[i][0] = i;
        for (int i = 0; i <= word2.size(); i++) f[0][i] = i;
        for (int i = 1; i <= word1.size(); i++) {
            for (int j = 1; j <= word2.size(); j++) {
                if (word1[i-1] == word2[j-1]) f[i][j] = f[i-1][j-1];
                else f[i][j] = min(f[i][j-1], min(f[i-1][j], f[i-1][j-1]))+1;
            }
        }
        return f[word1.size()][word2.size()];
    }
};

 C#

public class Solution {
    public int MinDistance(string word1, string word2) {
        int[,] f = new int[word1.Length+1, word2.Length+1];
        for (int i = 0; i <= word1.Length; i++) f[i, 0] = i;
        for (int i = 0; i <= word2.Length; i++) f[0, i] = i;
        for (int i = 1; i <= word1.Length; i++) {
            for (int j = 1; j <= word2.Length; j++) {
                if (word1[i-1] == word2[j-1]) f[i, j] = f[i-1, j-1];
                else f[i, j] = Math.Min(f[i, j-1], Math.Min(f[i-1, j], f[i-1, j-1])) + 1;
            }
        }
        return f[word1.Length, word2.Length];
    }
}