Submission #2539

#	Time	Username	Problem	Language	Result	Execution time	Memory
2539		kipa00	지우개 (GA4_eraser)	C++98	100 / 100	16 ms	3228 KiB

eraser

#include <cstdio>
using namespace std;

const int divider = 1000000007;

int N;
long long int a[100001];
long long int b[100001];
long long int c[100001];

int main() {
    int i, max = -1;
    int sum = 0;
    long long int s;
    scanf("%d", &N);
    for (i=0; i<N; ++i) {
        int tmp;
        scanf("%d", &tmp);
        ++a[tmp];
        if (max < tmp) {
            max = tmp;
        }
    }
    for (i=1; i<=max; ++i) {
        b[i] = b[i-1] + (a[i] * i);
        b[i] %= divider;
    }
    for (i=1; i<=max; ++i) {
        long long int tmp = b[max] - b[i];
        if (tmp < 0) {
            tmp += divider;
        }
        c[i] = c[i-1] + (a[i] * i * tmp);
        c[i] %= divider;
    }
    for (i=1; i<=max; ++i) {
        long long int tmp = c[max] - c[i];
        if (tmp < 0) {
            tmp += divider;
        }
        s = a[i] * i * tmp;
        sum += s % divider;
        sum %= divider;
    }
    if (sum < 0) {
        sum += divider;
    }
    printf("%d\n", sum);
    return 0;
}

• Subtask 1: 6 / 6
• Subtask 2: 7 / 7
• Subtask 3: 16 / 16
• Subtask 4: 17 / 17
• Subtask 5: 26 / 26
• Subtask 6: 28 / 28