Merge pull request #1 from algorithm001/master

Update data

Author: jacoesad

.gitignore

@@ -0,0 +1,2 @@
+.idea
+.vscode

Week_01/id_0/TestPush.java

@@ -0,0 +1,5 @@
+public class TestPush {
+	public static void main(String[] args) {
+		System.out.println("Hello Geekbang~~");
+	}
+}

Week_01/id_1/LeetCode24.java

@@ -0,0 +1,44 @@
+class Solution {
+
+    ListNode prePairTail = null;
+
+    public ListNode swapPairs(ListNode head) {
+
+        if (head == null) {
+            return null;
+        }
+
+        if (head.next == null) {
+            return head;
+        }
+
+        ListNode result = head.next;
+        
+        ListNode node = head;
+        ListNode next = head.next;
+        while (node != null && next != null) {
+
+            node = swap(node, next);
+
+            if (node == null) {
+                break;
+            }
+            next = node.next;
+        }
+        return result;
+
+    }
+
+    private ListNode swap(ListNode node, ListNode next) {
+
+        ListNode tmpNext = next.next;
+        next.next = node;
+        node.next = tmpNext;
+        if (prePairTail != null) {
+            prePairTail.next = next;
+        }
+        prePairTail = node;
+        return tmpNext;
+    }
+
+}

Week_01/id_1/LeetCode25.java

@@ -0,0 +1,75 @@
+
+class Solution {
+
+    ListNode preGroupTail = null;
+    ListNode result = null;
+
+    public ListNode reverseKGroup(ListNode head, int k) {
+
+        if (head == null || head.next == null || k == 1) {
+            return head;
+        }
+
+        int index = 1;
+        ListNode groupHead = head;
+        ListNode groupTail = head;
+
+        while (true) {
+
+            if (index != k) { // 查找 k 个节点中的 head 和 tail 节点
+                groupTail = groupTail.next;
+                if (groupTail != null) {
+                    index ++;
+                    continue;
+                }else {
+                    // 链表长度小于 K 的情况
+                    if (this.preGroupTail != null) {
+                        this.preGroupTail.next = groupHead;
+                        break;
+                    }else {
+                        return head;
+                    }
+                }
+            }else { 
+                // 个数达到 k 时执行交换，返回下一组的 head 节点
+                ListNode node = this.swap(groupHead, groupTail);
+                if (node == null) {
+                    break;
+                }
+                groupHead = node;
+                groupTail = node;
+                index = 1;
+            }
+        }
+        return result;
+    }
+
+    private ListNode swap(ListNode head, ListNode tail) {
+
+        // 反转链表
+        ListNode preNode = null;
+        ListNode currentNode = head;
+        while (currentNode != tail) {
+            ListNode next = currentNode.next;
+            currentNode.next = preNode;
+            preNode = currentNode;
+            currentNode = next;
+        }
+
+        // 当前组的 tail 节点执行 swap
+        ListNode node= currentNode.next;
+        currentNode.next = preNode;
+
+        // 反转完成，将上一组的 tail 节点指向当前组的 head 节点
+        // 第一次反转时上一组 tail 为 null，因此要执行判空操作
+        if (this.preGroupTail != null) {
+            this.preGroupTail.next = currentNode;
+        }else {
+            // 上一组的 tail 为空说明是第一组执行交换
+            // 结果一定是第一组交换后的 head 节点
+            result = currentNode;
+        }
+        this.preGroupTail = head;
+        return node;
+    }
+}

Week_01/id_102/leetcode_153_102.cpp

@@ -0,0 +1,37 @@
+/*
+* 存两个临时变量，left和right, 如果left>right,则返回right;
+* 如果只有一个元素，则返回它自己；
+* 如果没有旋转过，则返回第一个元素
+*/
+class Solution {
+public:
+    int findMin(vector<int>& nums) {
+        int count = nums.size();
+        if (count == 1) {
+            return nums[0];
+        }
+            
+        int left  = nums[0];
+        int right = nums[1];
+        if (left > right) {
+            return right;    
+        }
+        
+        int i;
+        for (i = 2; i < count; i++) {
+            left  = right;
+            right = nums[i];
+            
+            if (left > right) {
+                return right;    
+            }
+        }
+        
+        if (i == count) {
+            return nums[0];
+        }
+        
+        return -1;
+    }
+};
+

Week_01/id_102/leetcode_20_102.cpp

@@ -0,0 +1,35 @@
+/*
+* 堆栈实现
+* 满足三个条件则有效
+* 1. “左” 压栈
+* 2. “右” 在栈顶查找匹配的括号, 如果找到弹出栈顶字符，否则返回false
+* 3. 最终"栈" 为空, 返回true, "栈" 非空, 返回false
+* 注意，对于第一次输入是')','}'或者']'的情况，一定要判断堆栈是否为空，否则会数组越界
+*/
+
+class Solution {
+    
+public:
+    bool isValid(string s) {
+        vector<char> stack;   
+        map<char, char> spouse;
+        
+        spouse[')'] = '(';
+        spouse['}'] = '{';
+        spouse[']'] = '[';
+        
+        for (int i = 0; i< s.size(); ++i) {
+            if (s[i] =='(' || s[i] =='[' || s[i] =='{') {
+                stack.push_back(s[i]);
+            } else {
+                if (stack.empty() || spouse[s[i]] != stack[stack.size()-1]) {
+                    return false;
+                }
+                stack.pop_back();
+            } 
+        }
+        
+        return stack.empty();
+    }
+};
+

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;
+    }
+}