URAL1291. Gear-wheels

１２９１

不知道为嘛被分在ＤＰ里了　瞎写　注意没被别的轮带动的情况　初始为０　　分母为１

#include <iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
#include<stdlib.h>
#include<vector>
#include<queue>
using namespace std;
#define N 1010
vector<int>ge[N];
int co[N],d[N],vis[N];
struct node
{
    int f,nu,de;
}p[N];
int gcd(int a,int b)
{
    return b==0?a:gcd(b,a%b);
}
void init(int x,int y)
{
    int n1 = co[x]*p[x].nu,n2 = co[y]*p[x].de;
    if(n1==0||n2==0) n2=1;
    else
    {
        int k = gcd(n1,n2);
        n1 = n1/k;n2 = n2/k;
    }
    if(d[y]==1)
    p[y].f = 1;
    else
    p[y].f = -1;
    p[y].nu = n1;
    p[y].de = n2;
}
void bfs(int u)
{
    queue<int>q;
    q.push(u);
    while(!q.empty())
    {
        int tu = q.front();
        q.pop();
        for(int i = 0 ; i < (int)ge[tu].size() ; i++)
        {
            int v = ge[tu][i];
            if(!vis[v])
            {
                vis[v] = 1;
                d[v] = -d[tu];
                init(tu,v);
                q.push(v);
            }
        }
    }
}
int main()
{
    int i,n,s,v;
    scanf("%d",&n);
    for(i = 1; i <= n ; i++)
    {
        scanf("%d",&co[i]);
        int a;
        while(scanf("%d",&a)&&a)
        ge[i].push_back(a);
    }
    scanf("%d%d",&s,&v);
    d[s] = 1;
    p[s].f = 1;
    p[s].nu = v;
    p[s].de = 1;
    vis[s] = 1;
    bfs(s);
    for(i = 1; i <= n ; i++)
    {
        if(p[i].f==-1&&p[i].nu)
        printf("-");
        if(p[i].nu==0)
        p[i].de = 1;
        printf("%d/%d
",p[i].nu,p[i].de);
    }
    return 0;
}