35 lines
727 B
C++
35 lines
727 B
C++
#include <stdio.h>
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#include <vector>
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#include <string>
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#include <algorithm>
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#include <queue>
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#include <cstring>
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#include <map>
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#include <set>
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#include <iostream>
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#include <cmath>
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using namespace std;
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const int MAXN = 100005;
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int main()
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{
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int n;
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double a, p, b;
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double f0, f1, p0, p1;
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while (scanf("%d%lf%lf%lf", &n, &p, &a, &b))
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{
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if (n==0 && a==0 && p==0 && b==0) break;
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p /= 100.0;
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f0 = min(a, b);
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f1 = 0.0;
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for (int i = 1; i< n; ++i)
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{
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p0 = min(f0+b, a+p*f0+(1.0-p)*f1);
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p1 = p*f0+(1.0-p)*f1;
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f0 = p0;
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f1 = p1;
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}
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printf("%.4lf\n", f1);
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}
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return 0;
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}
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