问题描述
import java.util.*;
import java.io.*;
public class CarFueling {
static int compute_refills(int dist,int tank,int stops[],int n){
int current_refills=0;
int num_refills=0;
int last_refill=0;
while(current_refills<=n) {
last_refill = current_refills;
while ((current_refills <= n) && (stops[current_refills + 1] - stops[last_refill]) <= tank) {
current_refills = current_refills + 1;
}
if (current_refills == last_refill)
return -1;
if (current_refills <= n)
num_refills = num_refills + 1;
}
return num_refills;
}
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
int dist = scanner.nextInt();
int tank = scanner.nextInt();
int n = scanner.nextInt();
int stops[] = new int[n*n*n];// to solve array index out of bound exception increase the size of the array
for (int i = 0; i < n; i++) {
stops[i] = scanner.nextInt();
}
System.out.println(compute_refills(dist,tank,stops,n));
}
}
我认为while循环条件有些问题。
输入:
950
400
4
200375550750
我的输出:
1
正确的输出:
2
解决方法
如果你看
(current_refills <= n) && (stops[current_refills + 1] ... )
部分,两件事:
-
current_refills <= n
对n-1
(n元素数组的最后一个元素,因为第一个元素的索引为0)和n
(已在数组外部)都成立) - 然后
stops[current_refills + 1]
访问元素“后”,在这两种情况下,元素的数量比最大值高1或2个元素。
但是实际上这是可行的,只是您可以在旅程开始时添加0,在旅程结束时添加dist
:
int n = scanner.nextInt();
int stops[] = new int[n+2];
stops[0] = 0; // well,it is 0 already
stops[n+1] = dist;
for (int i = 1; i <= n; i++) {
stops[i] = scanner.nextInt();
}
然后compute_refills()
可能会正常工作(尽管我尚未检查)。