python/TangDou/XiTi/1368.cpp

#include <bits/stdc++.h>

using namespace std;


#pragma region C++实现的单链表通用模板
// https://blog.csdn.net/wonggonghong/article/details/21716597
// C++实现的单链表通用模板
// https://blog.csdn.net/wonggonghong/article/details/21527577
//创建一个单链表结构，包含一些常见的操作
struct Node {
    int element;  //节点存储信息可以根据需要修改！
    Node *next;
};

//创建一个空表，并返回表头
Node *CreateLists() {
    Node *head = new Node;
    head->next = NULL;
    return head;
}

//删除表头为head的该链表
void DeleteLists(Node *head) {
    Node *P = head->next, *temp;
    head->next = NULL;
    while (P) {
        temp = P->next;
        delete P;
        P = temp;
    }
}

//判断是不是最后一个链表节点
bool IsLast(Node *P) {
    return P->next == NULL;
}

//按值X进行查询，找到第一个
Node *Find(int X, Node *head) {
    Node *P = head->next;
    while (P && P->element != X)
        P = P->next;
    return P;
}

//按值X进行查询，找到符合条件的前一个节点
Node *FindPrevious(int X, Node *head) {
    Node *P = head;
    while (P->next && P->next->element != X)
        P = P->next;
    return P;
}

//按值X进行删除
void Delete(int X, Node *head) {
    Node *P = FindPrevious(X, head), *temp; //如果没找到X，则返回的是链表最后一项
    if (P->next) {
        temp = P->next;
        P->next = temp->next;
        delete temp;
    }
}

//在节点P后面插入X
void Insert(Node *P, int X) {
    Node *tempX = new Node;
    tempX->element = X;
    tempX->next = P->next;
    P->next = tempX;
}

//输出链表中所有元素的值
void OutputLists(Node *head) {
    Node *P = head->next;
    while (P) {
        std::cout << P->element << "   ";
        P = P->next;
    }
    std::cout << std::endl;
}


// 带头节点的单链表元素互换
void DoExchange(Node *A, Node *B, Node *head) {
    if (A == B)
        return;
    Node *PreA = FindPrevious(A->element, head);
    Node *PreB = FindPrevious(B->element, head);
    Node *PostA = A->next;
    Node *PostB = B->next;
    //先考虑A、B节点相邻的情况
    if (PostA == B) {
        PreA->next = B;
        B->next = A;
        A->next = PostB;
        return;
    }
    if (PostB == A) {
        PreB->next = A;
        A->next = B;
        B->next = PostA;
        return;
    }
    //再考虑其他情况
    PreA->next = B;
    B->next = PostA;
    PreB->next = A;
    A->next = PostB;
}

#pragma endregion C++实现的单链表通用模板


int main() {
    int n, m, p;
    cin >> n >> m >> p;

    //头节点
    Node *head = CreateLists();
    Node *P = head; //P为一个链表的指针，用它来进行移动
    //读入第一个数字，做为head头
    cin >> head->element;

    //第二行为n个不相同的数字-->创建链表
    for (int i = 1; i < n; i++) {
        int temp;
        cin >> temp;
        //插入数据
        Insert(P, temp); //P为移动的指针,Data[i]为每一个数据
        //移动P，方便下一次插入数据
        P = P->next;
    }
    //处理m行读入数据
    for (int i = 0; i < m; ++i) {
        int a, b;
        cin >> a >> b;
        //交换两个位置的数据
        Node *A = head;
        Node *B = head;
        for (int j = 1; j < a; ++j) {
            A = A->next;
        }
        for (int j = 1; j < b; ++j) {
            B = B->next;
        }
        DoExchange(A, B, head);
    }
    //输出第p个位置的数字
    Node *A = head;
    for (int i = 1; i < p; ++i) {
        A = A->next;
    }
    cout << A->element << endl;
    return 0;
}