Merge pull request algorithm004-01#409 from alexwei12/master

melody-li · web-flow · commit 6f1bb2728718 · 2019-10-28T11:51:46.000+08:00
136-Week 02
diff --git a/Week 02/id_136/LeetCode_1_136.java b/Week 02/id_136/LeetCode_1_136.java
@@ -0,0 +1,30 @@
+
+
+import java.util.HashMap;
+
+public class LeetCode_1_136 {
+
+    public int[] twoSum(int[] nums, int target) {
+        HashMap<Integer, Integer> map = new HashMap();
+        for (int i = 0; i < nums.length; i++) {
+            map.put(Integer.valueOf(nums[i]), i);
+        }
+
+        for (int i = 0; i < nums.length; i++) {
+            Integer index = map.get(target - nums[i]);
+            if (index != null && index.intValue() != i) {
+                return new int[]{i, index.intValue()};
+            }
+        }
+        return null;
+    }
+
+    public static void main(String[] args) {
+        int[] ns = {2,7,11,15};
+
+        int[] ints = new LeetCode_1_136().twoSum(ns, 9);
+        for (int i = 0; i < ints.length; i++) {
+            System.out.println(i + ",");
+        }
+    }
+}
diff --git a/Week 02/id_136/LeetCode_236_136.java b/Week 02/id_136/LeetCode_236_136.java
@@ -0,0 +1,24 @@
+import java.util.ArrayList;
+import java.util.Arrays;
+
+public class lowestCommonAncestorOfABinaryTree {
+    public TreeNode lowestCommonAncestor(TreeNode root, TreeNode A, TreeNode B) {
+        if (root == null || root == A || root == B) {
+            return root;
+        }
+        TreeNode left = lowestCommonAncestor(root.left, A, B);
+        TreeNode right = lowestCommonAncestor(root.right, A, B);
+        if (left != null && right != null) {
+            return root;
+        }
+
+        if (left != null) {
+            return left;
+        }
+
+        if (right != null) {
+            return right;
+        }
+        return null;
+    }
+}
diff --git a/Week 02/id_136/LeetCode_94_136.java b/Week 02/id_136/LeetCode_94_136.java
@@ -0,0 +1,37 @@
+
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Stack;
+
+public class LeetCode_94_136 {
+
+    public List<Integer> inorderTraversal(TreeNode root) {
+        List<Integer> l = new ArrayList<Integer>();
+        Stack<TreeNode> stack = new Stack();
+        TreeNode node = root;
+
+        while (!stack.isEmpty() || node != null) {
+            if (node != null) {
+                stack.push(node);
+                node = node.left;
+            } else {
+                if (!stack.isEmpty()) {
+                    node = stack.pop();
+                    l.add(node.val);
+                    node = node.right;
+                }
+            }
+        }
+        return l;
+    }
+}
+class TreeNode {
+    int val;
+    TreeNode left;
+    TreeNode right;
+
+    TreeNode(int x) {
+        val = x;
+    }
+}
