uva 1025 城市里的间谍

 1 #include<iostream>
 2 #include<cstdio>
 3 #include<cstring>
 4 #include<cmath>
 5 #include<cstdlib>
 6 #include<vector>
 7 #include<queue>
 8 #include<algorithm>
 9 #define inf 2147483611
10 #define ll long long 
11 #define MAXN 55
12 #define MOD
13 using namespace std;
14 inline int read()
15 {
16     int x=0,f=1;
17     char ch;ch=getchar();
18     while(!isdigit(ch)) {if(ch==‘-‘) f=-1;ch=getchar();}
19     while(isdigit(ch)) {x=x*10+ch-‘0‘;ch=getchar();}
20     return x*f;
21 }
22 int n,t[MAXN],m,x,dp[MAXN][MAXN*5];
23 bool larv[MAXN][MAXN*4],rarv[MAXN][MAXN*4];
24 int main()
25 {
26     freopen("spy.in","r",stdin);
27     freopen("spy.out","w",stdout);
28     n=read();
29     int tm=read();
30     for(int i=1;i<n;i++) t[i]=read();
31     m=read();
32     for(int i=1;i<=m;i++)
33     {
34         x=read();
35         for(int j=1;j<=n&&x<=tm;j++) {larv[j][x]=1;x+=t[j];}
36     }
37     m=read();
38     for(int i=1;i<=m;i++)
39     {
40         x=read();
41         for(int j=n;j>=1&&x<=tm;j--) {rarv[j][x]=1;x+=t[j-1];}
42     }
43     memset(dp,127,sizeof(dp));
44     dp[1][0]=0;
45     for(int i=1;i<=tm;i++)
46     {
47         for(int j=1;j<=n;j++)    
48         {
49             dp[j][i]=dp[j][i-1]+1;
50             if(larv[j][i]) dp[j][i]=min(dp[j][i],dp[j-1][i-t[j-1]]);
51             if(rarv[j][i]) dp[j][i]=min(dp[j][i],dp[j+1][i-t[j]]);
52         }
53     }
54     if(dp[n][tm]>=2139062143) printf("impossible");
55     else printf("%d",dp[n][tm]);
56     return 0;
57 }