02-线性结构3 Reversing Linked List (25分)

Posted 2020-12-14 2018shawn

02-线性结构3 Reversing Linked List (25分)

 Given a constant K and a singly linked list L, you are supposed to reverse the links of every K elements on L. For example, given L being 1→2→3→4→5→6, if K=3, then you must output 3→2→1→6→5→4; if K=4, you must output 4→3→2→1→5→6.

Input Specification:

Each input file contains one test case. For each case, the first line contains the address of the first node, a positive N (≤) which is the total number of nodes, and a positive K (≤) which is the length of the sublist to be reversed. The address of a node is a 5-digit nonnegative integer, and NULL is represented by -1.

Then N lines follow, each describes a node in the format:

Address Data Next

 

where Address is the position of the node, Data is an integer, and Next is the position of the next node.

Output Specification:

For each case, output the resulting ordered linked list. Each node occupies a line, and is printed in the same format as in the input.

Sample Input:

00100 6 4
00000 4 99999
00100 1 12309
68237 6 -1
33218 3 00000
99999 5 68237
12309 2 33218

Sample Output:

00000 4 33218
33218 3 12309
12309 2 00100
00100 1 99999
99999 5 68237
68237 6 -1

 

提交代码:

#include <stdio.h>
#include <stdlib.h>

#define Null -1
#define MAXSIZE 100000

typedef int ElemType;
typedef int Ptr;

struct LISTNODE {
    ElemType key;
    int next;
}list[MAXSIZE];

int GetLength(Ptr start) {
    int count = 0;
    Ptr next = start;
    while (next != Null) {
        count++;
        next = list[next].next;
    }
    return count;
}

//返回新的起始地址
int Reverse(Ptr p, int k) {
    int count = 0;
    Ptr cur, next, tmp;
    cur = p;
    next = list[cur].next;
    for (int i = 0; i < k - 1; ++i) {
        tmp = list[next].next;
        list[next].next = cur;
        cur = next;
        next = tmp;
    }
    list[p].next = next;
    return cur;
}

int ReverseWholeList(int firstPos, int len, int k)
{
    if (len >= k) {
        int startPos;//记录开始反转的第一个位置
        int lastPos;//记录上次反转后的最后一个位置
        //第一次反转
        startPos = firstPos;
        firstPos = Reverse(startPos, k);
        lastPos = startPos;//反转后第一个位置变为最后一个位置
        startPos = list[startPos].next;//反转后，第一个位置变为反转序列最后一个位置，取下个起始位置
        //第二次到最后一次反转
        for (int i = 1; i < len / k; ++i)
        {
            list[lastPos].next = Reverse(startPos, k);
            lastPos = startPos;
            startPos = list[startPos].next;
        }
    }
    return firstPos;
}
void Print(Ptr firstPos) {
    Ptr next = firstPos;
    if(next == -1){
        return;
    }
    while (list[next].next != Null) {
        printf("%05d %d %05d
", next, list[next].key, list[next].next);
        next = list[next].next;
    }
    printf("%05d %d %d
", next, list[next].key, list[next].next);
}
int main() {
    int firstPos;
    int N;
    int k;
    scanf("%d %d %d", &firstPos, &N, &k);
    int addr, data, next;
    for (int i = 0; i < N; ++i) {
        scanf("%d %d %d", &addr, &data, &next);
        list[addr].key = data;
        list[addr].next = next;
    }
    int len = GetLength(firstPos);
    firstPos = ReverseWholeList(firstPos, len, k);
    Print(firstPos);
    return 0;
}

结果：