Update 072._edit_distance.md

Author: 0xkookoo

docs/Leetcode_Solutions/072._edit_distance.md

@@ -120,3 +120,12 @@ class Solution(object):
                 dp[i][j] = min(dp[i-1][j]+1, dp[i][j-1]+1, dp[i-1][j-1]+tmp_dist)
         return dp[-1][-1]
 ```
+
+或者你愿意麻烦，可以这样初始化dp矩阵
+
+```
+dp = [[0 for j in range(len(word2)+1)] for i in range(len(word1)+1)]
+dp[0] = [i for i in range(len(word2)+1)]
+for i in range(len(word1)+1):
+    dp[i][0] = i
+```