1074 Reversing Linked List

link

#include <iostream>
#define LL long long
using namespace std;

int N,K;
int nextadd[100000];
int val[100000];

int helper(int head){
    int cur=head;
    int cnt=1;
    if(cnt==K) return head;
    while(true){
        cur=nextadd[cur];
        cnt++;
        if(cur==-1) return head;
        if(cnt==K) break;
    }
    int nextpartstart=-1;
    if(nextadd[cur]!=-1) nextpartstart=helper(nextadd[cur]);
    nextadd[cur]=-1;
    int pre=-1;
    int curpartend=head;
    cur=head;
    while(cur!=-1){
        int tmpnext=nextadd[cur];
        nextadd[cur]=pre;
        pre=cur;
        cur=tmpnext;
    }
    nextadd[curpartend]=nextpartstart;
    return pre;
}

int main(){
    int head;
    cin>>head;
    cin>>N>>K;
    for(int i=1;i<=N;i++){
        int add,value,next;
        cin>>add>>value>>next;
        val[add]=value;
        nextadd[add]=next;
    }
    int newhead=helper(head);
    int cur=newhead;
    while(cur!=-1){
        if(nextadd[cur]!=-1) printf("%05d %d %05d
", cur,val[cur],nextadd[cur]);
        else printf("%05d %d -1
", cur,val[cur]);
        cur=nextadd[cur];
    }
    return 0;
}