19 lines
512 B
C++
19 lines
512 B
C++
#include<stdio.h>
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#include<cmath>
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int main()
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{
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int HP1, HP2, AP1, AP2, N1, N2;
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while(scanf("%d%d%d%d", &HP1, &HP2, &AP1, &AP2) != EOF){
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double ans = 0, tmp = 0;
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N1 = (HP2 - 1) / AP1 + 1;
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N2 = (HP1 - 1) / AP2 + 1;
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ans = pow(0.5, N1);
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for(int i = 1; i < N2; ++i){
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tmp += log10(N1 - 1.0 + i) - log10(i * 1.0);
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ans += pow(10, tmp + (N1 + i) * log10(0.5));
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}
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printf("%.4lf\n", ans * 100);
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}
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return 0;
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}
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