Submission #7898

#	TimeUTC-0	Username	Problem	Language	Result	Execution time	Memory
7898	2014-08-24 02:48:02	gs14004	지우개 (GA4_eraser)	C++98	46 / 100	24 ms	2648 KiB

eraser

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#include <cstdio>
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];
    }
    long long res = 0;
    for (int i=1; i<=1000; i++) {
        for (int j=i+1; j<=1000; j++) {
            res += a[i] * a[j] * (sum[100000] - sum[j]);
            res %= mod;
        }
    }
    printf("%lld",res);
    // iCnti
    
 
 
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• Subtask 2: 7 / 7
• Subtask 3: 16 / 16
• Subtask 4: 17 / 17
• Subtask 5: 0 / 26
• Subtask 6: 0 / 28