usaco-2.4-comhome-pass

恶补了好几天的算法，英文版看得更懂，呵呵：

/*
ID: qq104801
LANG: C++
TASK: comehome
*/

#include <iostream>
#include <fstream>
#include <cstring>
#include <vector>
#include <list>
#include <set>
#include <queue>
#include <cstdio>
#include <algorithm>
#include <cmath>

#define NMAX 52
#define INF 99999

using namespace std;

int p;
int gg[NMAX][NMAX];
int dd[NMAX];
int vv[NMAX];
int result;

int change(char cc)
{
    int index=-1;
    if(cc>='A' && cc<='Z')
        index=cc-'A';
    else if(cc>='a' && cc<='z')
        index=cc-'a'+26;
    else index=-1;
    return index;
}

int dijkstra(int s)
{
    int min,k;
    for(int i=0;i<NMAX;i++)
    {
        vv[i]=false;
        dd[i]=gg[s][i];
    }
    dd[s]=0;
    vv[s]=1;
    for(int i=0;i<NMAX;i++)
    {
        min=INF;
        for(int j=0;j<NMAX;j++)
            if(!vv[j] && dd[j]<min)
            {
                min=dd[j];
                k=j;
            }
        vv[k]=1;
        for(int j=0;j<NMAX;j++)
            if(!vv[j] && (min+gg[k][j]<dd[j]))
            {
                dd[j]=min+gg[k][j];            
            }
    }
    int mmin=INF;
    for(int i=0;i<NMAX;i++)
    {
        if(dd[i]<mmin && i>=0 && i<=25 && dd[i]>0)
        {
            mmin=dd[i];
            result=i;
        }
    }
    return mmin;
}

void test()
{    
    freopen("comehome.in","r",stdin);
    freopen("comehome.out","w",stdout);
    
    char ca,cb;
    int d;

    for(int i=0;i<NMAX;i++)
    {
        gg[i][i]=INF;
        for(int j=0;j<NMAX;j++)
            gg[i][j]=INF;
    }
    memset(vv,0,sizeof(vv));   

    cin>>p;
    while(p--)
    {
        cin>>ca>>cb>>d;
        int ia=change(ca);
        int ib=change(cb);
        if(d<gg[ia][ib])
        {
            gg[ia][ib]=d;
            gg[ib][ia]=d;
        }
    }

    int ans=dijkstra(25);
    char first='A'+result;
    cout<<first<<" "<<ans<<endl;
}

int main () 
{        
    test();        
    return 0;
}

test data:

USER: cn tom [qq104801]
TASK: comehome
LANG: C++

Compiling...
Compile: OK

Executing...
   Test 1: TEST OK [0.008 secs, 3384 KB]
   Test 2: TEST OK [0.005 secs, 3384 KB]
   Test 3: TEST OK [0.003 secs, 3384 KB]
   Test 4: TEST OK [0.008 secs, 3384 KB]
   Test 5: TEST OK [0.008 secs, 3384 KB]
   Test 6: TEST OK [0.014 secs, 3384 KB]
   Test 7: TEST OK [0.032 secs, 3384 KB]
   Test 8: TEST OK [0.008 secs, 3384 KB]
   Test 9: TEST OK [0.005 secs, 3384 KB]

All tests OK.

Your program ('comehome') produced all correct answers! This is your submission #3 for this problem. Congratulations!

Here are the test data inputs:

------- test 1 ----
4
d Z 10
b d 2
A b 4
C d 5
------- test 2 ----
25
m Z 1000
A m 1000
B m 999
C m 998
D m 997
E m 996
F m 995
G m 994
H m 993
I m 992
J m 991
K m 990
L m 989
M m 988
N m 987
O m 986
P m 985
Q m 984
R m 983
S m 982
T m 981
U m 980
V m 979
W m 978
X m 977
------- test 3 ----
28
Z a 1000
a b 1000
b c 1000
c d 1000
d e 1000
e f 1000
f g 1000
g h 1000
h i 1000
i j 1000
j k 1000
k l 1000
l m 1000
m n 1000
n o 1000
o p 1000
p q 1000
q r 1000
r s 1000
s t 1000
t u 1000
u v 1000
v w 1000
w x 1000
x y 1000
y z 1000
z A 1000
A B 1000
------- test 4 ----
51
A a 836
B b 836
C c 836
D d 836
E e 836
F f 836
G g 836
H h 836
I i 836
J j 836
K k 836
................