3-05. Calculate the last K of the chained linear table (15) (used by STL List)

Link: http://pat.zju.edu.cn/contests/ds/3-05

For a series of positive integers, design an algorithm that is as efficient as possible to find the number at the last K position.

Input format description:

The input first gives a positive integer k, followed by several positive integers, and finally ends with a negative integer (the negative number is not included in the sequence, do not process ).

Output format description:

Output data at the last K position. If this location does not exist, the output error message is "null ".

Sample input and output:

Serial number	Input	Output
1	4 1 2 3 4 5 6 7 8 9 0 -1	7
2	6 3 6 7 8 2 -2	NULL

PS:

Not too familiar with the use of list shoes please stamp: http://blog.csdn.net/u012860063/article/details/39784005

The Code is as follows:

#include <cstdio>#include <cstring>#include <algorithm>#include <list>using namespace std;int main(){    list<int> LIST;    int k, tt;    int cont = 0;    int ans = -1;    scanf("%d",&k);    while(1)    {        scanf("%d",&tt);        if( tt < 0)            break;        LIST.push_back(tt);        cont++;        if(cont >= k)        {            ans = LIST.front();            LIST.pop_front();        }    }    if(ans == -1)        printf("NULL\n");    else        printf("%d\n",ans);    return 0;}

3-05. Calculate the last K of the chained linear table (15) (used by STL List)