add

5.leetcode/src/com/fanxb/common/Q105.java

@@ -0,0 +1,23 @@
+package com.fanxb.common;
+
+import java.util.HashMap;
+import java.util.Map;
+
+public class Q105 {
+    public TreeNode buildTree(int[] preorder, int[] inorder) {
+        Map<Integer, Integer> map = new HashMap<>(inorder.length);
+        for (int i = 0; i < inorder.length; i++) map.put(inorder[i], i);
+        return buildTree(preorder, map, 0, preorder.length - 1, 0, inorder.length - 1);
+    }
+
+    public TreeNode buildTree(int[] preorder, Map<Integer, Integer> map, int pL, int pR, int iL, int iR) {
+        if (pL > pR) return null;
+        TreeNode root = new TreeNode(preorder[pL]);
+        int rs = map.get(root.val);
+        //前序左边子树结束位置
+        int newPr = pL + rs - iL;
+        root.left = buildTree(preorder, map, pL + 1, newPr, iL, rs - 1);
+        root.right = buildTree(preorder, map, newPr + 1, pR, rs + 1, iR);
+        return root;
+    }
+}

5.leetcode/src/com/fanxb/common/Q106.java

@@ -0,0 +1,26 @@
+package com.fanxb.common;
+
+import java.util.HashMap;
+import java.util.Map;
+
+public class Q106 {
+    public TreeNode buildTree(int[] inorder, int[] postorder) {
+        Map<Integer, Integer> map = new HashMap<>();
+        for (int i = 0; i < inorder.length; i++) {
+            map.put(inorder[i], i);
+        }
+        return buildTree(postorder, map, 0, postorder.length - 1, 0, inorder.length - 1);
+    }
+
+    private TreeNode buildTree(int[] pre, Map<Integer, Integer> map, int pL, int pR, int iL, int iR) {
+        if (pL > pR || iL > iR) return null;
+        TreeNode root = new TreeNode(pre[pR]);
+        int index = map.get(pre[pR]);
+        System.out.println(index);
+        int newPr = pL + index - iL - 1;
+        root.left = buildTree(pre, map, pL, newPr, iL, index - 1);
+        root.right = buildTree(pre, map, newPr + 1, pR - 1, index + 1, iR);
+        return root;
+    }
+
+}

5.leetcode/src/com/fanxb/common/Q82.java

@@ -0,0 +1,45 @@
+package com.fanxb.common;
+
+public class Q82 {
+    public ListNode deleteDuplicates(ListNode head) {
+        if (head == null || head.next == null) return head;
+        ListNode res = new ListNode(), last = res, startBefore = null;
+        res.next = head;
+        while (head.next != null) {
+            if (head.val == head.next.val) {
+                if (startBefore == null)
+                    startBefore = last;
+                last = head;
+            } else if (startBefore != null) {
+                last = startBefore;
+                startBefore.next = head.next;
+                startBefore = null;
+            } else {
+                last = head;
+            }
+            head = head.next;
+        }
+        if (startBefore != null) startBefore.next = null;
+        return res.next;
+    }
+
+    public ListNode better(ListNode head) {
+        ListNode res = new ListNode();
+        res.next = head;
+        ListNode cur = res.next, last = res;
+        while (cur != null && cur.next != null) {
+            if (cur.val == cur.next.val) {
+                int x = cur.next.val;
+                while (cur != null && cur.val == x) {
+                    last.next = cur.next;
+                    cur = cur.next;
+                }
+            } else {
+                last = cur;
+                cur = cur.next;
+            }
+        }
+        return res.next;
+
+    }
+}