Merge pull request #1368 from xiaofei-2020/dp50

添加（0072.编辑距离.md）：增加typescript版本

problems/0072.编辑距离.md

@@ -327,5 +327,42 @@ const minDistance = (word1, word2) => {
 };
 ```
 
+TypeScript：
+
+```typescript
+function minDistance(word1: string, word2: string): number {
+    /**
+        dp[i][j]: word1前i个字符，word2前j个字符，最少操作数
+        dp[0][0]=0：表示word1前0个字符为'', word2前0个字符为''
+     */
+    const length1: number = word1.length,
+        length2: number = word2.length;
+    const dp: number[][] = new Array(length1 + 1).fill(0)
+        .map(_ => new Array(length2 + 1).fill(0));
+    for (let i = 0; i <= length1; i++) {
+        dp[i][0] = i;
+    }
+    for (let i = 0; i <= length2; i++) {
+        dp[0][i] = i;
+    }
+    for (let i = 1; i <= length1; i++) {
+        for (let j = 1; j <= length2; j++) {
+            if (word1[i - 1] === word2[j - 1]) {
+                dp[i][j] = dp[i - 1][j - 1];
+            } else {
+                dp[i][j] = Math.min(
+                    dp[i - 1][j],
+                    dp[i][j - 1],
+                    dp[i - 1][j - 1]
+                ) + 1;
+            }
+        }
+    }
+    return dp[length1][length2];
+};
+```
+
+
+
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