用链表写（超时）：

#pragma warning(disable:4996)
#include<stdio.h>
#include<stdlib.h>
typedef struct LNode {
	int data;
	struct LNode* next;
}LNode,*LinkList;

int InitList(LinkList& L)
{
	if (L == NULL)
	{
		return 0;
	}
	L->next = NULL;
	return 1;
}

void List_Create(LinkList& L, int n)
{
	LNode* Temp,*list=L;
	for (int i = 0; i < n; ++i)
	{
		Temp = (LNode*)malloc(sizeof(LNode));
		if (Temp == NULL)
			exit(1);
		scanf("%d", &Temp->data);
		Temp->next = NULL;
		list->next = Temp;
		list = Temp;
	}
}

int Find_List(LinkList L, int m)
{
	LNode* node = L->next;
	int j = 1;
	while (node != NULL && j < m)
	{
		node = node->next;
		j++;
	}
	if (node != NULL)
	{
		printf("%d\n", node->data);
		return 1;
	}
	return -1;
}

int main()
{
	LNode* L;
	L = (LNode*)malloc(sizeof(LNode));
	InitList(L);

	int n, m;
	scanf("%d %d", &n, &m);

	List_Create(L, n);
	
	int query;
	for (int i = 0; i < m; ++i)
	{
		scanf("%d", &query);
		if (Find_List(L, query) == -1)
		{
			printf("ERROR");
		}
	}
	free(L);
	return 0;
	
}

数组写（AC）：

#pragma warning(disable:4996)
#include <stdio.h>
#include <stdlib.h>

int main() {
    int n, m;
    scanf("%d %d", &n, &m);
    
    int *students = (int*)malloc(n * sizeof(int));
    if (students == NULL) {
        printf("Memory allocation failed.\n");
        return 1;
    }

  
    for (int i = 0; i < n; i++) {
        scanf("%d", &students[i]);
    }

  
    int query;
    for (int i = 0; i < m; i++) {
        scanf("%d", &query);
        if (query > 0 && query <= n) {
            printf("%d\n", students[query - 1]);  // 数组索引从0开始，因此要减1
        } else {
            printf("ERROR\n");  // 查询超出范围
        }
    }

    // 清理内存
    free(students);
    return 0;
}