Merge pull request #1 from algorithm001/master

sync remote

Author: xuyunbo

.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_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;
+    }
+}

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_127/21.jpeg

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+/**
+ * Definition for singly-linked list.
+ * public class ListNode {
+ *     int val;
+ *     ListNode next;
+ *     ListNode(int x) { val = x; }
+ * }
+ */
+class Solution {
+    public ListNode mergeTwoLists(ListNode l1, ListNode l2) {
+        if (l1 == null)
+            return l2;
+        if (l2 == null)
+            return l1;
+
+        ListNode cur1 = l1;
+        ListNode cur2 = l2;
+        ListNode mergeCur = null;
+        ListNode mergeHead = null;
+
+        if (cur1.val <= cur2.val) {
+            mergeCur = cur1;
+            mergeHead = cur1;
+            cur1 = cur1.next;
+        } else {
+            mergeCur = cur2;
+            mergeHead = cur2;
+            cur2 = cur2.next;
+        }
+
+        while (cur1 != null && cur2 != null) {
+            if (cur1.val <= cur2.val) {
+                mergeCur.next = cur1;
+                cur1 = cur1.next;
+            } else {
+                mergeCur.next = cur2;
+                cur2 = cur2.next;
+            }
+            mergeCur=mergeCur.next;
+        }
+
+        if (cur1 != null) {
+            mergeCur.next = cur1;
+        }
+
+        if (cur2 != null) {
+            mergeCur.next = cur2;
+        }
+
+        return mergeHead;
+    }
+
+    /**
+     * 递归思路没有想到，参考网上的相关答案，理解之后写出
+     */
+    public ListNode mergeTowListsRecursive(ListNode l1, ListNode l2) {
+        if (l1 == null)
+            return l2;
+        if (l2 == null)
+            return l1;
+
+
+        if (l1.val <= l2.val) {
+            ListNode head = l1;
+            head.next = mergeTowListsRecursive(l1.next, l2);
+            return head;
+        } else {
+            ListNode head = l2;
+            head.next = mergeTowListsRecursive(l1, l2.next);
+            return head;
+        }
+    }
+}

Week_01/id_127/83.jpeg

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+/**
+ * Definition for singly-linked list.
+ * public class ListNode {
+ *     int val;
+ *     ListNode next;
+ *     ListNode(int x) { val = x; }
+ * }
+ */
+class Solution {
+    public ListNode deleteDuplicates(ListNode head) {
+        ListNode cur = head;
+        while (cur != null && cur.next != null) {
+            if (cur.val == cur.next.val) {
+                cur.next = cur.next.next;
+            } else {
+                cur = cur.next;
+            }
+        }
+        return head;
+    }
+}

Week_01/id_127/LeetCode_21_127.java

@@ -1 +1,8 @@
-# 学习笔记
+# 学习笔记
+
+### LeetCode-83思路：
+
+见图片: `83.jpeg`
+
+### LeetCode-21思路：
+