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Author: dingjikerbo

README.md

@@ -372,4 +372,5 @@
 |560|[Subarray Sum Equals K](https://leetcode.com/problems/subarray-sum-equals-k/)| [Java](https://github.com/dingjikerbo/leetcode/blob/master/solution/src/main/java/com/inuker/solution/SubarraySumEqualsK.java)|70||
 |637|[Average of Levels in Binary Tree](https://leetcode.com/problems/average-of-levels-in-binary-tree/#/description)| [Java](https://github.com/dingjikerbo/leetcode/blob/master/solution/src/main/java/com/inuker/solution/AverageOfLevelsInBinaryTree.java)|100||
 |652|[Find Duplicate Subtrees](https://leetcode.com/problems/find-duplicate-subtrees/)| [Java](https://github.com/dingjikerbo/leetcode/blob/master/solution/src/main/java/com/inuker/solution/FindDuplicateSubtrees.java)|70|开始还没思路|
-|653|[Two Sum IV - Input is a BST](https://leetcode.com/problems/two-sum-iv-input-is-a-bst/)| [Java](https://github.com/dingjikerbo/leetcode/blob/master/solution/src/main/java/com/inuker/solution/TwoSumIV.java)|90||
+|653|[Two Sum IV - Input is a BST](https://leetcode.com/problems/two-sum-iv-input-is-a-bst/)| [Java](https://github.com/dingjikerbo/leetcode/blob/master/solution/src/main/java/com/inuker/solution/TwoSumIV.java)|90||
+|684|[Redundant Connection](https://leetcode.com/problems/redundant-connection/)| [Java](https://github.com/dingjikerbo/leetcode/blob/master/solution/src/main/java/com/inuker/solution/RedundantConnection.java)|||

solution/src/main/java/com/inuker/solution/RedundantConnection.java

@@ -0,0 +1,34 @@
+package com.inuker.solution;
+
+/**
+ * Created by liwentian on 2017/12/7.
+ */
+
+/**
+ * https://leetcode.com/articles/redundant-connection/
+ */
+public class RedundantConnection {
+    /**
+     * 思路很简单，发现第一个联通的边时就是多余的
+     */
+    public int[] findRedundantConnection(int[][] edges) {
+        int[] arr = new int[2001];
+        for (int i = 0; i < arr.length; i++) {
+            arr[i] = i;
+        }
+        for (int[] edge : edges) {
+            int from = edge[0], to = edge[1];
+            int from0 = find(arr, from), to0 = find(arr, to);
+            if (from0 == to0) {
+                return edge;
+            }
+            arr[from0] = to0;
+        }
+        return new int[2];
+    }
+
+    private int find(int[] nums, int i) {
+        for ( ; nums[i] != i; i = nums[i]);
+        return i;
+    }
+}