【leetcode】 Edit Distance

问题描述：

 Given two words word1 and word2, find the minimum number of steps required to convert word1 to word2. (each operation is counted as 1 step.)

You have the following 3 operations permitted on a word:

a) Insert a character
b) Delete a character
c) Replace a character

问题解析：

方式1.用递归+回朔。运行造成LTE。

方式2.DP。参考BOLG:http://blog.youkuaiyun.com/beiyetengqing/article/details/8105180

ac代码：

public int minDistance(String word1, String word2) {
		 if(word1.length()==0)
			 return word2.length();
		 if(word2.length()==0)
			 return word1.length();
		 int[][] result = new int[word1.length()+1][word2.length()+1];
		 for(int i=0;i<=word2.length();i++){
			 result[0][i]=i;
		 }
		 for(int j=0;j<=word1.length();j++){
			 result[j][0]=j;
		 }
		 
		 for(int i=1;i<word1.length()+1;i++){
			 for(int j=1;j<word2.length()+1;j++){
				 if(word1.charAt(i-1)==word2.charAt(j-1)){
					 result[i][j]=result[i-1][j-1];
				 }else{
					 result[i][j]=
							 Math.min(result[i-1][j]+1, Math.min(result[i][j-1]+1,
									 result[i-1][j-1]+1));
				 }
			 }
		 }
		 return result[word1.length()][word2.length()];
	 }