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risk-management.cpp
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risk-management.cpp
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#include<iostream>
#include<cmath>
#include<cstring>
#include<ctime>
#include<limits>
#include<cfloat>
using namespace std;
const int MAXN = 300 + 1;
double a[MAXN][MAXN], x[MAXN], g[MAXN], nx[MAXN], tmp[MAXN];
double eval(int n, double x[])
{
double ret = 0;
for (int i = 1; i <= n; i++)
for (int j = 1; j <= n; j++)
ret += x[i] * x[j] * a[i][j];
return ret;
}
double ans;
double bestx[MAXN];
void foo(int n)
{
double score = eval(n, x);
int test = 100;
while (test--)
{
double best = DBL_MIN;
int bestidx = 0;
for (int i = 1; i <= n; i++)
{
double tmp = score;
for (int j = 1; j <= n; j++)
{
if (i != j)
tmp -= 4 * a[i][j] * x[i] * x[j];
}
if (tmp > best)
{
best = tmp;
bestidx = i;
}
}
if (best <= score)
break;
score = best;
x[bestidx] = -x[bestidx];
}
if (score > ans)
{
ans = score;
memcpy(bestx, x, sizeof(x));
}
}
int main()
{
int n;
cin >> n;
for (int i = 1; i <= n; i++)
for (int j = 1; j <= n; j++)
cin >> a[i][j];
ans = DBL_MIN;
int test = 100;
while (test--)
{
for (int i = 1; i <= n; i++)
{
int rnd = rand();
if (1.0 * rnd / RAND_MAX > 0.5)
x[i] = -1;
else
x[i] = 1;
}
foo(n);
}
for (int i = 1; i <= n; i++)
cout << bestx[i] << " ";
cout << endl;
return 0;
}