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12-LinkList/21-SwapPairs/12-SeltWriteSwapPairs/LinkList.cpp

+#include <iostream>
+#include <list>
+#include<algorithm>
+#include<stdlib.h>
+#include <string.h>
+#include <vector>
+using namespace std;
+
+
+typedef int DataType;
+class ListNode {
+public:
+    DataType data;
+    ListNode *next;
+    ListNode() : data(0), next(nullptr) {}
+    ListNode(DataType x) : data(x), next(nullptr) {}
+    ListNode(DataType x, ListNode *next) : data(x), next(next) {}
+};
+
+class LinkList {
+public:
+    ListNode *m_Head;
+
+    LinkList() {
+        m_Head = nullptr; 
+    }
+    ~LinkList()
+    {
+        DeleteAll();
+    }
+
+    void Initiate();
+    void DeleteAll();
+
+    void listHeadCreate(); 
+    ListNode * listHeadCreate(vector<int> nums);
+    void printList(); 
+    ListNode * reverse(ListNode *pHead);
+    ListNode* swapPairs(ListNode* head);
+};
+
+void LinkList::DeleteAll() {
+    ListNode *pNode = m_Head;
+    ListNode *nextNode;
+    while(pNode != nullptr) {
+        nextNode = pNode->next;
+	delete pNode;
+	pNode = nextNode;
+    }
+    m_Head = nullptr;
+}
+
+void LinkList::Initiate() {
+    DeleteAll();
+    m_Head = nullptr;
+}
+
+ListNode * LinkList::listHeadCreate(vector<int> nums) {
+    DeleteAll();
+    ListNode *newNode,*pNode,*rNode;
+    pNode = nullptr;
+    for(int i = 0; i< nums.size(); i++) {
+        ListNode *newNode = new ListNode;
+	newNode->data = nums[i];
+	//cout << nums[i] << endl;
+	newNode->next = nullptr;
+	if(pNode == nullptr) {
+	    pNode = newNode;
+	    rNode = newNode;
+	} else {
+	    rNode->next = newNode;
+	    rNode = newNode;
+	}
+    }
+    rNode->next = nullptr;
+    return pNode;
+}
+
+void LinkList::listHeadCreate() {
+    DeleteAll();
+    ListNode *newNode,*pNode,*rNode;
+    pNode = nullptr;
+    for(int i = 0;i<=10;i++) {
+        ListNode *newNode = new ListNode;
+	newNode->data = i;
+	newNode->next = nullptr;
+	if(pNode == nullptr) {
+	    pNode = newNode;
+	    rNode = newNode;
+	} else {
+	    rNode->next = newNode;
+	    rNode = newNode;
+	}
+    }
+    rNode->next = nullptr;
+    m_Head = pNode;
+}
+
+ListNode * LinkList::swapPairs(ListNode *headNode) {
+    //终止条件：链表只剩一个节点或者没节点了，没得交换了.返回的是已经处理好的链表
+    if(headNode == nullptr || headNode->next == nullptr) {
+        return headNode;
+    }
+    //一共三个节点:headNode, nextNode, swapPairs(nextNode->next)
+    //下面的任务便是交换这3个节点中的前两个节点
+    ListNode *nextNode = headNode->next;
+    headNode->next = swapPairs(nextNode->next);
+    nextNode->next = headNode;
+    //根据第二步：返回给上一级的是当前已经完成交换后，即处理好了的链表部分
+    return nextNode;
+}
+
+ListNode *LinkList::reverse(ListNode *pHead) {
+    if(pHead == nullptr) {
+        return nullptr;
+    }
+    ListNode *tmp = nullptr;
+    ListNode *pre = nullptr;
+    while(pHead) {
+        tmp = pHead->next;
+	pHead->next = pre;
+	pre = pHead;
+	pHead = tmp;
+    }
+    return pre;
+}
+
+void LinkList::printList() {
+    ListNode *pNode;    
+    //pNode = m_Head->next;
+    pNode = m_Head;
+    cout << "LinkList traversal:" << endl;
+    cout << "       ";
+    while(pNode != nullptr) {
+        cout << pNode->data << " ";
+	pNode = pNode->next;
+    }
+    cout << endl;
+}
+
+vector<int> Str2Int(char *str) {
+    vector<int> nums;
+    const char *split = ",";
+    char *p = strtok(str,split);
+
+    int val;
+    while(p!=nullptr) {
+        sscanf(p,"%d",&val); 
+	nums.push_back(val);
+	p = strtok(nullptr, split);
+    }
+
+    cout << "Str2Int output:";
+    for(int i = 0; i< nums.size(); i++)
+    {
+        cout << nums[i] << " ";
+    }
+    cout << endl;
+
+    return nums;
+}
+
+string StrProcess(string str) {
+    int pos1 = str.find("[");
+    int pos2 = str.find("]");
+    string newStr = str.substr(pos1+1, pos2-pos1-1);  
+    //newStr.erase(std::remove(newStr.begin(), newStr.end(), ','), newStr.end());
+
+    return newStr;
+}
+#define N 200
+int main() {
+#if 0
+    char str[1000] = { 0 };
+    cin.getline(str, 1000);
+    cout << str << endl;
+#else
+    char str[N] = {"head = [1,2,3,4,5,6,7,8,9,10]"};
+#endif
+    string data(str); //String 就是这个指针, 因此需要赋值字符串.
+
+    data = StrProcess(data);
+    cout << data << endl;
+
+    int i;
+    for(i=0;i<data.length();i++)
+    {
+       str[i] = data[i]; 
+    }
+    str[i] = '\0'; 
+    char *p = str;
+
+    vector<int> nums;
+    nums = Str2Int(p);
+
+    LinkList *sol = new LinkList;
+    sol->Initiate();
+    cout << "----------Create begin--------------" << endl;
+    sol->m_Head = sol->listHeadCreate(nums); 
+    sol->printList();
+    cout << "----------Create end--------------" << endl;
+
+#if 0
+    ListNode *dummy = new ListNode(0);
+    dummy->next = sol->m_Head;
+    sol->printList();
+    sol->swapPairs(dummy);
+    sol->m_Head = dummy->next;
+    sol->printList();
+#else
+    sol->printList();
+    cout << "----------swapPairs begin--------------" << endl;
+    //如果只执行:
+    //    sol->swapPairs(sol->m_Head); 
+    //而不对m_Head重新赋值:
+    //    sol->m_Head = sol->swapPairs(sol->m_Head);
+    //那么由于m_Head还指向原来的位置,就会从第二个节点开始打印，从而打印时少了一个元素；
+    sol->m_Head = sol->swapPairs(sol->m_Head);
+    sol->printList();
+    cout << "----------swapPairs end--------------" << endl;
+#endif
+
+    cout << "----------reverse begin--------------" << endl;
+    //这里要像上面的swapPairs一样:记得给m_Head重新赋值；
+    //否则reverse也会出错
+    sol->m_Head = sol->reverse(sol->m_Head);
+    sol->printList();
+    cout << "----------reverse end--------------" << endl;
+
+    return EXIT_SUCCESS;
+}