为什么这个在oj上显示运行错误啊

Question

#include <stdio.h>

int main () {
struct imformation {
char name[20];
int a;
int b;
int c;
int sum;
} student[4];
int i, j;
for (i = 0; i < 3; i++) {
scanf("%s %d %d %d", student[i].name, &student[i].a, &student[i].b, &student[i].c);
student[i].sum = 0;
student[i].sum = student[i].a + student[i].b + student[i].c;
}

for (i = 0; i < 3; i++) {
    for (j = i + 1; j < 3; j++) {
        if (student[i].sum < student[j].sum) {
            student[4] = student[i];
            student[i] = student[j];
            student[j] = student[4];
        }
    }
}
for (i = 0; i < 3; i++) {
    printf("%s %.2f\n", student[i].name, (student[i].sum) / 3.0);
}
return 0;

}

Answer 1

student[4] = student[i];
student[i] = student[j];
student[j] = student[4];
改成
student[3] = student[i];
student[i] = student[j];
student[j] = student[3];
下标从0开始，student长度为4，最大的下标是3