Submission #7900

#	Time	Username	Problem	Language	Result	Execution time	Memory
7900		gs14004	지우개 (GA4_eraser)	C++98	100 / 100	28 ms	2648 KiB

eraser

#include <cstdio>
#include <cstdlib>
int n;
long long a[100005];
long long sum[100005];
long long mod = 1e9+7;
int main(){
    int t;
    scanf("%d",&n);
    for (int i=0; i<n; i++) {
        scanf("%d",&t);
        a[t]++;
    }
    for (int i=1; i<=100000; i++) {
        a[i] *= i;
        a[i] %= mod;
    }
    for (int i=1; i<=100000; i++) {
        sum[i] = a[i] + sum[i-1];
        sum[i] %= mod;
    }
    for (int i=1; i<=100000; i++) {
        sum[i] = a[i] * (sum[100000] - sum[i]);
        sum[i] %= mod;
    }
    for (int i=1; i<=100000; i++) {
        sum[i] += sum[i-1];
        sum[i] %= mod;
    }
    long long res = 0;
    for (int i=1; i<=100000; i++) {
        res += a[i] * (sum[100000] - sum[i]);
        res %= mod;
    }
    if(res < 0) res += mod;
    printf("%lld",res);
    // iCnti
    
}

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