Merge pull request #2 from algorithm001/master

合并主分支的内容

Author: AHaoPang

Week_01/id_122/LeetCode_142_122.py

@@ -0,0 +1,26 @@
+# Definition for singly-linked list.
+# class ListNode(object):
+#     def __init__(self, x):
+#         self.val = x
+#         self.next = None
+
+class Solution(object):
+    def detectCycle(self, head):
+        """
+        :type head: ListNode
+        :rtype: ListNode
+        """
+        if head is None or head.next is None or head.next.next is None:
+            return
+        p1 = head.next
+        p2 = head.next.next
+        while(p2 is not None and p2.next is not None and p2.next.next is not None):
+            p1 = p1.next
+            p2 = p2.next.next
+            if p1 is p2:
+                p1 = head
+                while p1 is not p2:
+                    p1 = p1.next
+                    p2 = p2.next
+                return p1
+        return 

Week_01/id_122/LeetCode_21_122.php

@@ -0,0 +1,75 @@
+<?php
+/**
+ * Created by PhpStorm.
+ * User: yuanyunxu
+ * Date: 19/4/16
+ * Time: ÏÂÎç3:41
+ */
+
+/**
+ * Definition for a singly-linked list.
+ * class ListNode {
+ *     public $val = 0;
+ *     public $next = null;
+ *     function __construct($val) { $this->val = $val; }
+ * }
+ */
+
+class ListNode {
+    public $val = 0;
+    public $next = null;
+    function __construct($val) { $this->val = $val; }
+}
+
+class Solution {
+
+    /**
+     * @param ListNode $l1
+     * @param ListNode $l2
+     * @return ListNode
+     */
+    function mergeTwoLists($l1, $l2) {
+        if ($l1 == null) {
+            return $l2;
+        }
+
+        if ($l2 == null) {
+            return $l1;
+        }
+
+        $first = $l1;
+        $second = $l2;
+
+        if ($first->val <= $second->val) {
+            $head = $first;
+            $first = $first->next;
+        } else {
+            $head = $second;
+            $second = $second->next;
+        }
+
+        $now = $head;
+
+        while (true) {
+            if ($first == null) {
+                $now->next = $second;
+                break;
+            }
+            if ($second == null) {
+                $now->next = $first;
+                break;
+            }
+
+            if ($first->val <= $second->val) {
+                $now->next = $first;
+                $first = $first->next;
+                $now = $now->next;
+                continue;
+            }
+            $now->next = $second;
+            $second = $second->next;
+            $now = $now->next;
+        }
+        return $head;
+    }
+}

Week_01/id_122/LeetCode_24_122.php

@@ -0,0 +1,49 @@
+<?php
+/**
+ * Definition for a singly-linked list.
+ * class ListNode {
+ *     public $val = 0;
+ *     public $next = null;
+ *     function __construct($val) { $this->val = $val; }
+ * }
+ */
+class ListNode {
+    public $val = 0;
+    public $next = null;
+    function __construct($val) { $this->val = $val; }
+}
+
+class Solution {
+
+    /**
+     * @param ListNode $head
+     * @return ListNode
+     */
+    function swapPairs($head) {
+
+        //没有元素，或者只有一个元素
+        if ($head == null || $head->next == null) {
+            return $head;
+        }
+        $shaoBing = new ListNode(null);
+        $shaoBing->next = $head->next;
+
+        //到这里至少链表中至少有两个元素
+        $prev = $head;
+        $prior = $prev->next;
+        $next = $prior->next;
+
+        while ($next && $next->next) {
+            $prev->next = $next->next;
+            $prior->next = $prev;
+            $prev = $next;
+            $prior = $next->next;
+            $next = $prior->next;
+        }
+
+        //最后交换末尾两个元素, 针对单数个链表元素做处理
+        $prev->next = $next ? $next : null;
+        $prior->next = $prev;
+        return $shaoBing->next;
+    }
+}

Week_01/id_122/LeetCode_83_122.php

@@ -0,0 +1,46 @@
+<?php
+/**
+ * Created by PhpStorm.
+ * User: yuanyunxu
+ * Date: 19/4/16
+ * Time: ÏÂÎç3:15
+ */
+
+/**
+ * Definition for a singly-linked list.
+ * class ListNode {
+ *     public $val = 0;
+ *     public $next = null;
+ *     function __construct($val) { $this->val = $val; }
+ * }
+ */
+
+class ListNode {
+     public $val = 0;
+     public $next = null;
+     function __construct($val) { $this->val = $val; }
+}
+
+class Solution {
+
+    /**
+     * @param ListNode $head
+     * @return ListNode
+     */
+    function deleteDuplicates($head) {
+        if ($head == null) {
+            return $head;
+        }
+        $prior = $head;
+        while ($prior->next) {
+            $next = $prior->next;
+            if ($prior->val == $next->val) {
+                $prior->next = $next->next;
+                $next->next = null;
+                continue;
+            }
+            $prior = $prior->next;
+        }
+        return $head;
+    }
+}

Week_01/id_2/LeetCode_20_2.cs

@@ -0,0 +1,50 @@
+using System;
+using System.Collections;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace leetcode
+{
+    public class 有效的括号
+    {
+        public bool IsValid(string s)
+        {
+            Stack<char> ts = new Stack<char>();
+            Dictionary<char, char> dic = new Dictionary<char, char>();
+            dic.Add(')', '(');
+            dic.Add('}', '{');
+            dic.Add(']', '[');
+            foreach (var item in s)
+            {
+                if (dic.ContainsKey(item))
+                {
+                    if (ts.Count <= 0)
+                    {
+                        return false;
+                    }
+
+                    var left = ts.Pop();
+                    if (left != dic[item])
+                    {
+                        return false;
+                    }
+                }
+                else
+                {
+                    ts.Push(item);
+                }
+            }
+
+            if (ts.Count > 0)
+            {
+                return false;
+            }
+            else
+            {
+                return true;
+            }
+        }
+    }
+}

Week_01/id_2/LeetCode_21_2.cs

@@ -0,0 +1,50 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace leetcode.合并两个有序链表
+{
+    public class ListNode
+    {
+        public int val;
+        public ListNode next;
+        public ListNode(int x) { val = x; }
+    }
+
+    public class 合并两个有序链表
+    {
+        public ListNode MergeTwoLists(ListNode l1, ListNode l2)
+        {
+            ListNode head = new ListNode(int.MinValue);
+            ListNode tail = head;
+            while (l1 != null && l2 != null)
+            {
+                if (l1.val < l2.val)
+                {
+                    tail.next = l1;
+                    l1 = l1.next;
+                }
+                else
+                {
+                    tail.next = l2;
+                    l2 = l2.next;
+                }
+                tail = tail.next;
+            }
+
+            if (l1 != null)
+            {
+                tail.next = l1;
+            }
+
+            if (l2 != null)
+            {
+                tail.next = l2;
+            }
+            head = head.next;
+            return head;
+        }
+    }
+}

Week_01/id_2/LeetCode_24_2.cs

@@ -0,0 +1,55 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace leetcode.两两交换链表中的节点
+{
+
+    public class ListNode
+    {
+        public int val;
+        public ListNode next;
+        public ListNode(int x) { val = x; }
+    }
+
+    public class 两两交换链表中的节点
+    {
+        public ListNode SwapPairs(ListNode head)
+        {
+            ListNode a = new ListNode(int.MinValue);
+            ListNode b = head;
+            ListNode c = head?.next;
+            a.next = head;
+            head = a;
+
+            while (b != null && c != null)
+            {
+                var temp = c.next;
+                c.next = b;
+                b.next = temp;
+                a.next = c;
+                a = b;
+                b = b?.next;
+                c = b?.next;
+            }
+            head = head.next;
+
+            return head;
+        }
+
+        public ListNode SwapPairs_recursive(ListNode head)
+        {
+            if (head == null || head.next == null)
+            {
+                return head;
+            }
+
+            var next = head.next;
+            head.next = SwapPairs_recursive(next.next);
+            next.next = head;
+            return next;
+        }
+    }
+}

Week_01/id_2/LeetCode_503_2.cs

@@ -0,0 +1,31 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace leetcode
+{
+    public class 下一个更大元素_II
+    {
+        public int[] NextGreaterElements(int[] nums)
+        {
+            int[] result = new int[nums.Length];
+            for (int i = 0; i < nums.Length; i++)
+            {
+                result[i] = -1;
+                for (int j = 1; j < nums.Length; j++)
+                {
+                    var index = (i + j) % nums.Length;
+                    if (nums[index] > nums[i])
+                    {
+                        result[i] = nums[index];
+                        break;
+                    }
+                }
+            }
+
+            return result;
+        }
+    }
+}