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#include "AppHdr.h"
#include "random-var.h"
#include "random.h"
random_var::random_var(int c)
: start(c), end(c+1)
{
weights.push_back(1);
init();
}
random_var::random_var(int s, int e, weight_func w)
: start(s), end(e)
{
init_weights(w);
init();
}
random_var::random_var(int s, int e, std::vector<int> ws)
: start(s), end(e), weights(ws)
{
ASSERT(weights.size() == static_cast<unsigned int>(end - start));
init();
}
const random_var& random_var::operator=(const random_var& other)
{
start = other.start;
end = other.end;
total = other.total;
weights = other.weights;
return (*this);
}
int random_var::weight(int val) const
{
if (val < start || val >= end)
return (0);
return (weights[val - start]);
}
void random_var::init_weights(weight_func w)
{
ASSERT(weights.empty());
for (int v = start; v < end; ++v)
weights.push_back(w ? (*w)(v) : 1);
}
void random_var::init()
{
total = 0;
for (int v = start; v < end; ++v)
total += weight(v);
ASSERT(total > 0);
ASSERT(weight(start) > 0 && weight(end - 1) > 0);
}
int random_var::roll2val(int r) const
{
ASSERT(0 <= r && r < total);
int v = start;
int w = weight(v);
while (r >= w)
{
v++;
w += weight(v);
}
return (v);
}
int random_var::roll() const
{
return (roll2val(random2(total)));
}
int random_var::max() const
{
return (end - 1);
}
int random_var::min() const
{
return (start);
}
double random_var::expected() const
{
double ev = 0;
for (int i = start; i < end; ++i)
ev += i * weight(i) / (double)total;
return (ev);
}
//////////////////////////////////
random_var constant(int n)
{
return (random_var(n));
}
random_var operator+(const random_var& x, const random_var& y)
{
const int start = x.min() + y.min();
const int end = x.max() + y.max() + 1;
std::vector<int> weights(end - start, 0);
for (int vx = x.min(); vx <= x.max(); ++vx)
for (int vy = y.min(); vy <= y.max(); ++vy)
weights[vx + vy - start] += x.weight(vx) * y.weight(vy);
return (random_var(start, end, weights));
}
random_var negate(const random_var& x)
{
const int start = -x.max();
const int end = -x.min() + 1;
std::vector<int> weights(end - start, 0);
for (int v = x.min(); v <= x.max(); ++v)
weights[-v - start] = x.weight(v);
return (random_var(start, end, weights));
}
random_var operator-(const random_var& x, const random_var& y)
{
return (x + negate(y));
}
const random_var& operator+=(random_var& x, const random_var& y)
{
x = x + y;
return (x);
}
const random_var& operator-=(random_var& x, const random_var& y)
{
x = x - y;
return (x);
}
random_var operator/(const random_var& x, int d)
{
const int start = x.min() / d;
const int end = x.max() / d + 1;
std::vector<int> weights(end - start, 0);
for (int v = x.min(); v <= x.max(); ++v)
weights[v/2 - start] += x.weight(v);
return (random_var(start, end, weights));
}
random_var rv::max(const random_var& x, const random_var& y)
{
const int start = std::max(x.min(), y.min());
const int end = std::max(x.max(), y.max()) + 1;
std::vector<int> weights(end - start, 0);
for (int vx = x.min(); vx <= x.max(); ++vx)
for (int vy = y.min(); vy <= y.max(); ++vy)
weights[std::max(vx, vy) - start] += x.weight(vx) * y.weight(vy);
return (random_var(start, end, weights));
}
random_var rv::min(const random_var& x, const random_var& y)
{
const int start = std::min(x.min(), y.min());
const int end = std::min(x.max(), y.max()) + 1;
std::vector<int> weights(end - start, 0);
for (int vx = x.min(); vx <= x.max(); ++vx)
for (int vy = y.min(); vy <= y.max(); ++vy)
weights[std::min(vx, vy) - start] += x.weight(vx) * y.weight(vy);
return (random_var(start, end, weights));
}
random_var rv::roll_dice(int d, int n)
{
if (n <= 0)
return (constant(0));
random_var x = constant(0);
for (int i = 0; i < d; ++i)
x += random_var(1, n+1);
return (x);
}
random_var rv::random2(int n)
{
return (random_var(0, std::max(n, 1)));
}
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