02-线性结构3 Reversing Linked List (25 分)

#include <cstdio>
#define Null -1

const int maxn = 1e5+2;
struct Node {
    int data;
    int addr, next;
} Lst[maxn];



int input(int , int);
int change(int k, int first);
void printList(int first);
bool rearCheck(int k, int start);
int reverse(int head, int k);

int main() {
    int first, n, k;
    scanf("%d%d%d", &first, &n, &k);
    
    int head = input(n, first);
    int NewStart = change(k, head);
    printList(NewStart);
    
    return 0;
}
int input(int n, int first) {
    for(int i=0; i<n; i++) {
        int taddr;
        scanf("%d", &taddr);
        scanf("%d%d", &Lst[taddr].data, &Lst[taddr].next);
        Lst[taddr].addr = taddr;
    }
    int p = 100000;
    Lst[p].next = first;
    return p;
}

int change(int k, int head) {
    int tmp = head;
    while( rearCheck(k, tmp) ) {
        Lst[tmp].next = reverse(tmp, k);
        
        for(int i=0; i<k; i++) {
            tmp = Lst[tmp].next;
        }
        
    }
    return head;
}

bool rearCheck(int k, int start) {
    int cnt = 0;
    while( cnt < k+1 ) {
        if(start == Null) break; 
        start = Lst[start].next;
        cnt++;
    } 
    
    if(cnt == k+1) return true;
    else return false;
}

int reverse(int head, int k) {
    int freshStart = Lst[head].next;
    int origStart = Lst[freshStart].next;
    int tmp;
    
    int cnt= 0;
    while(cnt < k-1) {
    
        tmp = Lst[origStart].next;
        Lst[origStart].next = freshStart;
        freshStart = origStart;
        origStart = tmp;
        cnt++;
        
    }
    Lst[Lst[head].next].next = origStart;
    
    return freshStart;
}


void printList(int p) {
    p = Lst[p].next;
    while(p!=-1) {
        if(Lst[p].next != -1)
            printf("%05d %d %05d\n", Lst[p].addr, Lst[p].data, Lst[p].next);
        else     
            printf("%05d %d -1\n", Lst[p].addr, Lst[p].data);
        p = Lst[p].next;
    }
}