Submission #7105

#	Time	Username	Problem	Language	Result	Execution time	Memory
7105		baneling100	지우개 (GA4_eraser)	C++98	100 / 100	16 ms	3432 KiB

eraser

#include <stdio.h>
#define MOD 1000000007

long long N, M, A[100001], B[100001], C[100001], Ans;

void input(void)
{
    long long i, temp;

    scanf("%lld",&N);
    for(i=1 ; i<=N ; i++)
    {
        scanf("%lld",&temp);
        A[temp]++;
        if(M<temp)
            M=temp;
    }
}

void process(void)
{
    long long i, sum=0;

    for(i=M ; i>=2 ; i--)
    {
        sum+=i*A[i];
        sum%=MOD;
        B[i-1]=(i-1)*sum*A[i-1];
        B[i-1]%=MOD;
    }
    sum=0;
    for(i=M-1 ; i>=2 ; i--)
    {
        sum+=B[i];
        sum%=MOD;
        C[i-1]=(i-1)*sum*A[i-1];
        C[i-1]%=MOD;
    }
    for(i=1 ; i<=M-2 ; i++)
    {
        Ans+=C[i];
        Ans%=MOD;
    }
}

void output(void)
{
    printf("%lld",Ans);
}

int main(void)
{
    input();
    process();
    output();

    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