Codeforces Round #451 (Div. 2) B. Proper Nutrition【枚举/扩展欧几里得/给你n问有没有两个非负整数x,y满足x·a + y·b = n】
1 second
256 megabytes
standard input
standard output
Vasya has n burles. One bottle of Ber-Cola costs a burles and one Bars bar costs b burles. He can buy any non-negative integer number of bottles of Ber-Cola and any non-negative integer number of Bars bars.
Find out if it's possible to buy some amount of bottles of Ber-Cola and Bars bars and spend exactly n burles.
In other words, you should find two non-negative integers x and y such that Vasya can buy x bottles of Ber-Cola and y Bars bars andx·a + y·b = n or tell that it's impossible.
First line contains single integer n (1 ≤ n ≤ 10 000 000) — amount of money, that Vasya has.
Second line contains single integer a (1 ≤ a ≤ 10 000 000) — cost of one bottle of Ber-Cola.
Third line contains single integer b (1 ≤ b ≤ 10 000 000) — cost of one Bars bar.
If Vasya can't buy Bars and Ber-Cola in such a way to spend exactly n burles print «NO» (without quotes).
Otherwise in first line print «YES» (without quotes). In second line print two non-negative integers x and y — number of bottles of Ber-Cola and number of Bars bars Vasya should buy in order to spend exactly n burles, i.e. x·a + y·b = n. If there are multiple answers print any of them.
Any of numbers x and y can be equal 0.
7
2
3
YES
2 1
100
25
10
YES
0 10
15
4
8
NO
9960594
2551
2557
YES
1951 1949
In first example Vasya can buy two bottles of Ber-Cola and one Bars bar. He will spend exactly 2·2 + 1·3 = 7 burles.
In second example Vasya can spend exactly n burles multiple ways:
- buy two bottles of Ber-Cola and five Bars bars;
- buy four bottles of Ber-Cola and don't buy Bars bars;
- don't buy Ber-Cola and buy 10 Bars bars.
In third example it's impossible to but Ber-Cola and Bars bars in order to spend exactly n burles.
【题意】:给你n问有没有两个非负整数x,y满足x·a + y·b = n。
【分析】:略带技巧的枚举。非负整数x,y上面做文章。
【代码】:
#include<bits/stdc++.h>
using namespace std;
int main()
{
int n,a,b;
cin>>n>>a>>b;
for(int i=;i*a<=n;++i)//自己这个地方是i<=n,错了,可能出现到负数的时候%b==0的情况
{
if((n-i*a)%b==)
{
int j=(n-i*a)/b;
puts("YES");
printf("%d %d\n",i,j);
exit();
}
}
puts("NO");
return ;
}
枚举,整数性判断
#include <bits/stdc++.h> using namespace std;
typedef long long int ll;
ll ex_gcd(ll a,ll b,ll &x,ll &y)
{
if(b==)
{
x=;
y=;
return a;
}
ll r=ex_gcd(b,a%b,x,y);
ll t=x;
x=y;
y=t-a/b*y;
return r;
}
bool jie(ll a,ll b,ll c,ll &x,ll &y)
{
ll r=ex_gcd(a,b,x,y);
if(c%r!=) return ;
ll zz=c/r;
x*=zz;
y*=zz;
if(x<&&y<) return ;
ll bb=b/r;
ll aa=a/r;
if(x<&&y>)
{
ll t=-*x/bb;
if(x+bb*t<) t++;
x=x+bb*t;
y=y-aa*t;
if(y>=) return ;
else return ;
}
else if(x>&&y<)
{
ll t=y/aa;
if(y-aa*t<) t--; x=x+bb*t;
y=y-aa*t;
if(x>=) return ;
else return ;
}
return ;
}
ll a,b,n,x,y;
int main()
{
while(~scanf("%lld%lld%lld",&n,&a,&b))
{
x=;
y=;
if(jie(a,b,n,x,y))
{
printf("YES\n");
printf("%lld %lld\n",x,y);
}
else
{
printf("NO\n");
}
}
return ;
}
拓展欧几里得
Codeforces Round #451 (Div. 2) B. Proper Nutrition【枚举/扩展欧几里得/给你n问有没有两个非负整数x,y满足x·a + y·b = n】的更多相关文章
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