ZOJ Problem Set - 3827Information Entropy
2014-10-14 11:39
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ZOJ Problem Set - 3827Information Entropy
题目链接
题目大意:给你一个公式,然后给你n个变量x,求出这些x代入公式所得的值之和。
解题思路:普通的利用数学函数求和,只是要知道x = 0的时候,结果等于0.
代码:
题目链接
题目大意:给你一个公式,然后给你n个变量x,求出这些x代入公式所得的值之和。
解题思路:普通的利用数学函数求和,只是要知道x = 0的时候,结果等于0.
代码:
#include <cstdio> #include <cstring> #include <cmath> const double esp = 1e-9; int main () { int T, n; double b, p; char str[10]; scanf ("%d", &T); while (T--) { scanf ("%d%s", &n, str); if (str[0] == 'b') b = 2; else if (str[0] == 'n') b = exp(1.0); else b = 10; double ans = 0; for (int i = 0; i < n; i++) { scanf ("%lf", &p); if (fabs(p) > esp) { p /= 100.0; ans += p * log(p) / log(b); } } printf ("%.12lf\n", -ans); } }
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