Merge pull request #745 from hhj233/distance_dp

feat: distance_dp-java

problems/为了绝杀编辑距离，卡尔做了三步铺垫.md

@@ -167,7 +167,33 @@ else {
 
 
 Java：
-
+```java
+class Solution {
+    public int minDistance(String word1, String word2) {
+        int m = word1.length();
+        int n = word2.length();
+        int[][] dp = new int[m+1][n+1];
+        for(int i = 1; i <= m; i++){
+            dp[i][0] = i;
+        }
+        for(int i = 1; i <= n; i++){
+            dp[0][i] = i;
+        }
+        for(int i = 1; i <= m; i++){
+            for(int j = 1; j <= n; j++){
+                int left = dp[i][j-1]+1;
+                int mid = dp[i-1][j-1];
+                int right = dp[i-1][j]+1;
+                if(word1.charAt(i-1) != word2.charAt(j-1)){
+                    mid ++;
+                }
+                dp[i][j] = Math.min(left,Math.min(mid,right));
+            }
+        }
+        return dp[m][n];
+    }
+}
+```
 
 Python：