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Language: Default It‘s not a Bug, It‘s a Feature!
Description It is a curious fact that consumers buying a new software product generally do not expect the software to be bug-free. Can you imagine buying a car whose steering wheel only turns to the right? Tinyware Inc. is one of those companies. After releasing a new word processing software this summer, they have been producing patches ever since. Only this weekend they have realized a big problem with the patches they released. While all patches fix some bugs, More formally, the situation looks like this. Tinyware has found a total of n bugs B = {b1, b2, ..., bn} in their software. And they have released m patches p1, p2, ..., pm. To apply patch pi to the software, the bugs Bi+ in B have to be present Tinyware‘s problem is a simple one. Given the original version of their software, which contains all the bugs in B, it is possible to apply a sequence of patches to the software which results in a bug- free version of the software? And if so, assuming that Input The input contains several product descriptions. Each description starts with a line containing two integers n and m, the number of bugs and patches, respectively. These values satisfy 1 <= n <= 20 and 1 <= m <= 100. This is followed by m lines describing the The first of these strings describes the bugs that have to be present or absent before the patch can be applied. The i-th position of that string is a ``+‘‘ if bug bi has to be present, a ``-‘‘ if bug bi has to be absent, and a `` 0‘‘ if it doesn‘t matter whether The second string describes which bugs are fixed and introduced by the patch. The i-th position of that string is a ``+‘‘ if bug bi is introduced by the patch, a ``-‘‘ if bug bi is removed by the patch (if it was present), and a ``0‘‘ if bug bi is not affected The input is terminated by a description starting with n = m = 0. This test case should not be processed. Output For each product description first output the number of the product. Then output whether there is a sequence of patches that removes all bugs from a product that has all n bugs. Note that in such a sequence a patch may be used multiple times. If there is such Print a blank line after each test case. Sample Input 3 3 1 000 00- 1 00- 0-+ 2 0-- -++ 4 1 7 0-0+ ---- 0 0 Sample Output Product 1 Fastest sequence takes 8 seconds. Product 2 Bugs cannot be fixed. Source |
这个题拿到手并不会做，没有好的思路，然后就看了网上的题解。第一次碰到不建图也能SPFA的，又学习了。另外这一题的位运算处理也非常巧妙，这是我不熟悉的，先放在这里，以后多来看几遍。
參考这两篇博客，写的非常好：http://www.cnblogs.com/scau20110726/archive/2012/12/16/2820739.html
http://www.cnblogs.com/staginner/archive/2011/10/25/2223489.html
代码：
#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
#include <cmath>
#include <string>
#include <map>
#include <stack>
#include <vector>
#include <set>
#include <queue>
#pragma comment (linker,"/STACK:102400000,102400000")
#define pi acos(-1.0)
#define eps 1e-6
#define lson rt<<1,l,mid
#define rson rt<<1|1,mid+1,r
#define FRE(i,a,b) for(i = a; i <= b; i++)
#define FREE(i,a,b) for(i = a; i >= b; i--)
#define FRL(i,a,b) for(i = a; i < b; i++)
#define FRLL(i,a,b) for(i = a; i > b; i--)
#define mem(t, v) memset ((t) , v, sizeof(t))
#define sf(n) scanf("%d", &n)
#define sff(a,b) scanf("%d %d", &a, &b)
#define sfff(a,b,c) scanf("%d %d %d", &a, &b, &c)
#define pf printf
#define DBG pf("Hi\n")
typedef long long ll;
using namespace std;
#define INF 0x3f3f3f3f
#define mod 1000000009
const int maxn = 25;
const int MAXN = 111;
const int MAXM = (1<<20)+100;
const int N = 1005;
char s1[maxn],s2[maxn];
int s[2][MAXN],t[2][MAXN],cost[MAXN];
int dist[MAXM];
bool inq[MAXM];
int n,m;
void SPFA()
{
int i,j;
mem(inq,false);
mem(dist,INF);
queue<int>Q;
int start=(1<<n)-1;
Q.push(start);
inq[start]=true;
dist[start]=0;
while (!Q.empty())
{
int u=Q.front(); Q.pop();
inq[u]=false;
for (i=0;i<m;i++)
{
if ((u|s[1][i])==u&&(u&s[0][i])==u)
{
int v=u;
v|=t[1][i];
v&=t[0][i];
if (dist[v]>dist[u]+cost[i])
{
dist[v]=dist[u]+cost[i];
if (!inq[v])
{
inq[v]=true;
Q.push(v);
}
}
}
}
}
// for(i=0;i<=start;i++)
// pf("%d ",dist[i]);
// pf("\n");
if (dist[0]==INF)
pf("Bugs cannot be fixed.\n");
else
pf("Fastest sequence takes %d seconds.\n",dist[0]);
}
int main()
{
#ifndef ONLINE_JUDGE
freopen("C:/Users/lyf/Desktop/IN.txt","r",stdin);
#endif
int i,j,cas=0;
while (sff(n,m))
{
if (n==0&&m==0) break;
mem(s,0);
mem(t,0);
for (i=0;i<m;i++)
{
scanf("%d%s%s",&cost[i],s1,s2);
for (j=0;j<n;j++)
{
if (s1[j]==‘+‘)
s[1][i]+=(1<<j);
if (s1[j]!=‘-‘)
s[0][i]+=(1<<j);
if (s2[j]==‘+‘)
t[1][i]+=(1<<j);
if (s2[j]!=‘-‘)
t[0][i]+=(1<<j);
}
}
pf("Product %d\n",++cas);
SPFA();
pf("\n");
}
return 0;
}
It's not a Bug, It's a Feature! (poj 1482 最短路SPFA+隐式图+位运算)