UVa 103 - Stacking Boxes

DAG上的动态规划，需要注意最后要打印起点到终点的一条路，因此状态d[i]定义为从 i 出发的最长路的距离。

UVa今天这是怎么了，两道题都是将近5min才出结果。

 1 # include <stdio.h>
 2 # include <string.h>
 3 # include <stdlib.h>
 4 
 5 # define MAXD 11
 6 # define MAXN 31
 7 
 8 int k, n;
 9 int d[MAXN];
10 int box[MAXN][MAXD];
11 int g[MAXN][MAXN];
12 
13 int cmp(const void *x, const void *y)
14 {
15     return (*(int *)x) - (*(int *)y);
16 }
17 
18 int dp(int i);
19 void print_order(int i);
20 
21 int main()
22 {
23     int i, j, p, fit, max, tm, mi;
24         
25     while (~scanf("%d%d", &k, &n))
26     {
27         for (i = 1; i <= k; ++i)
28         {
29             for (j = 0; j < n; ++j)
30                 scanf("%d", &box[i][j]);
31               qsort(box[i], n, sizeof(int), cmp);
32           }
33           
34           memset(g, 0, sizeof(g));
35           memset(d, 0, sizeof(d));
36           
37           for (i = 1; i <= k; ++i)
38           for (j = 1; j <= k; ++j)
39           {
40               fit = 1;
41               for (p = 0; p < n; ++p)
42                 if (box[i][p] <= box[j][p]) 
43                    {
44                       fit = 0;
45                       break;
46                 }
47              if (fit) g[i][j] = 1;
48           }
49                   
50           max = 0;
51           for (i = 1; i <= k; ++i)
52               if ((tm = dp(i)) > max) 
53             {
54                  max = tm;
55                  mi = i;
56             }
57            
58            printf("%d\n", max);
59            print_order(mi);
60            printf("\n");
61     }
62     
63     return 0;
64 }
65 
66 int dp(int i)
67 {
68     int j, t;
69     if (d[i] > 0) return d[i];
70     d[i] = 1;
71     for (j = 1; j <= k; ++j)
72         if (g[j][i])
73         {
74             t = dp(j) + 1;
75             if (d[i] < t) d[i] = t;
76            }
77        return d[i];    
78 }
79 
80 void print_order(int i)
81 {
82     int j;
83     printf("%d ", i);
84     for (j = 1; j <= k; ++j)
85         if (g[j][i] && d[i] == d[j]+1) 
86         {
87             print_order(j);
88             break;
89         }
90 }