Submission #2538

#	Time	Username	Problem	Language	Result	Execution time	Memory
2538		tncks0121	지우개 (GA4_eraser)	C++98	100 / 100	19 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, j, 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) % divider);
        b[i] %= divider;
    }
    for (j=1; j<=max; ++j) {
        c[j] = c[j-1] + ((a[j] * j) % divider) * (b[max] - b[j] + divider) % divider;
        c[j] %= divider;
    }
    for (i=1; i<=max; ++i) {
        s = ((a[i] * i) % divider) * (c[max] - c[i] + divider) % divider;
        sum += s % divider;
        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