33 lines
542 B
C
33 lines
542 B
C
#include <stdio.h>
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#define MOD 1000000007
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long long power(long long a, int n);
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int main() {
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int M;
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scanf("%d",&M);
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long long ans = 0;
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while(M--) {
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long long N, S;
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scanf("%lld %lld",&N, &S);
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ans += (S*power(N, MOD-2))%MOD;
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}
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printf("%lld\n", ans%MOD);
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return 0;
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}
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long long power(long long a, int n) {
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if(n==0) return 1;
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if(n==1) return a%MOD;
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long long temp = power(a, n/2);
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long long result = temp*temp%MOD;
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if(n%2) result = result*a%MOD;
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return result;
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} |