Leetcode 72编辑距离 C++

思路：动态规划。
具体规律及解释 参考http://www.cnblogs.com/grandyang/p/4344107.html

class Solution {
public:
    int minDistance(string word1, string word2) {
        int n1=word1.size(),n2=word2.size();
        int dp[n1+1][n2+1];
        dp[0][0]=0;
        for(int i=1;i<=n2;++i) dp[0][i]=i;
        for(int i=1;i<=n1;++i) dp[i][0]=i;
        for(int i=1;i<=n1;++i)
            for(int j=1;j<=n2;++j)
            {
                if(word1[i-1]==word2[j-1]) dp[i][j]=dp[i-1][j-1];
                else dp[i][j]=min(dp[i][j-1],min(dp[i-1][j-1],dp[i-1][j]))+1;
            }
        return dp[n1][n2];
        
    }
};