It's not a Bug, it's a Feature!

这道题的关键是二进制的或与运算~
现在特别感激计算机基础的老师给了我们做bomb实验，受益匪浅。
#include <iostream>
#include <bits/stdc++.h>
#define INF 0x3f3f3f3f
#define maxm 105
#define maxn ((1<<20)+1)
using namespace std;

struct Node
{
    int u,d;
    Node(int i,int j):u(i),d(j){}
    Node(){}
    bool operator < (const Node & a)const
    {
        return d>a.d;
    }
};

int n,m;
int c[maxm];//代价
int d[maxn];//距离
bool vis[maxn];
string s1[maxm],s2[maxm];//补丁

//是否匹配补丁
bool match(int u,int i)
{
    for(int j = 0;j<s1[i].size();j++)
    {
        if(s1[i][j]=='+') if(!(u&(1<<j))) return false;
        if(s1[i][j]=='-')  if(u&(1<<j)) return false;
    }
    return true;
}

//打完补丁后的状态
int change(int u,int i)
{
    //cout<<s2[i].size()<<endl;
    for(int j = 0;j<s2[i].size();j++)
    {
        if(s2[i][j]=='+') u = u|(1<<j);
        if(s2[i][j]=='-') u = u&(~(1<<j));
    }
    return u;
}

int dijkstra()
{
    priority_queue<Node>Q;
    memset(vis,0, sizeof(vis));
    memset(d,INF, sizeof(d));
    int u = (1<<n)-1;//初始状态++
    d[u] = 0;
    Q.push(Node(u,0));
    while (!Q.empty())
    {
        Node x = Q.top();Q.pop();
        u = x.u;
        if(vis[u]) continue;
        vis[u] = 1;
        if(u == 0) return d[u];//已经找到了
        for(int i = 0;i<m;i++)
        {
            if(match(u,i))
            {
                int v = change(u,i);//新的状态
                if(d[v]>d[u]+c[i])
                {
                    d[v] = d[u]+c[i];
                    Q.push(Node(v,d[v]));
                }
            }
        }
    }
    return -1;
}



int main() {
    int cost;
    int kase = 0;
    while (cin>>n>>m&&n+m)
    {
        for(int i = 0;i<m;i++)
        {
            cin>>c[i]>>s1[i]>>s2[i];
        }
        int ans = dijkstra();
        //if(kase++) cout<<endl;
        printf("Product %d\n",++kase);
        if(ans!=-1)
            printf("Fastest sequence takes %d seconds.\n\n",ans);
        else
            printf("Bugs cannot be fixed.\n\n");

    }
    return 0;
}
/**
3 3
1 000 00-
1 00- 0-+
2 0-- -++
4 1
7 0-0+ ----
0 0
 **/
It's not a Bug, it's a Feature!

猜你喜欢
