可以写出方程ax+by=n，对于该题来说，首先有x>=0, y>=0；其次x要么尽量大，要么尽量小。
以下是我的代码：
#include <iostream>
#include <cstdio>
#include <cmath>
using namespace std;
typedef long long int64;
int64 Gcd ( int64 a, int64 b )
{
for ( int64 t = a % b; t; a = b, b = t, t = a % b ); return b;
}
void ExpandGcd ( int64 a, int64 b, int64 &d, int64 &x, int64 &y )
{
if ( b ) { ExpandGcd ( b, a % b, d, y, x ); y -= a / b * x; }
else { d = a; x = 1; y = 0; }
}
int main ( )
{
#ifndef ONLINE_JUDGE
freopen ( "data.in", "r", stdin );
#endif
int64 n, n1, n2, c1, c2;
int64 d, x0, y0, x1, y1, x2, y2, ansx, ansy;
while ( cin >> n && n )
{
cin >> c1 >> n1 >> c2 >> n2;
// Input
d = Gcd ( n1, n2 );
if ( n % d )
{
printf ( "failed\n" );
continue;
}
n /= d; n1 /= d; n2 /= d;
ExpandGcd ( n1, n2, d, x0, y0 );
x0 *= n;
y0 *= n;
int64 a = (int64)ceil ( -(double)x0 / n2 ), b = (int64)floor ( (double)y0 / n1 );
if ( a > b )
{
printf ( "failed\n" );
continue;
}
x1 = x0 + n2 * a;
y1 = y0 - n1 * a;
x2 = x0 + n2 * b;
y2 = y0 - n1 * b;
if ( x1 * c1 + y1 * c2 < x2 * c1 + y2 * c2)
{
ansx = x1;
ansy = y1;
}
else
{
ansx = x2;
ansy = y2;
}
// Solve
cout << ansx << " " << ansy <<endl;
// Output
}
return 0;
}
posted on 2011-09-06 18:34
lee1r 阅读(618)
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题目分类：数学/数论