toj 4070 简单dp

 1 #include <iostream>
 2 #include <cstring>
 3 #include <cstdio>
 4 using namespace std;
 5 
 6 const int INF = 1 << 29;
 7 const int N = 21;
 8 char road[N];
 9 int cost[N];
10 
11 void init()
12 {
13     cost[0] = 0;
14     for ( int i = 1; i < N; i++ ) cost[i] = INF;
15 }
16 
17 bool check( int i, int j )
18 {
19     if ( road[i] == ‘R‘ && road[j] == ‘G‘ ) return true;
20     if ( road[i] == ‘G‘ && road[j] == ‘B‘ ) return true;
21     if ( road[i] == ‘B‘ && road[j] == ‘R‘ ) return true;
22     return false;
23 }
24 
25 int main ()
26 {
27     int t;
28     scanf("%d", &t);
29     while ( t-- )
30     {
31         scanf("%s", road);
32         int len = strlen(road);
33         init();
34         for ( int i = 0; i < len - 1; i++ )
35         {
36             for ( int j = i + 1; j < len; j++ )
37             {
38                 if ( check( i, j ) )
39                 {
40                     int tmp = cost[i] + ( j - i ) * ( j - i );
41                     if ( tmp < cost[j] ) cost[j] = tmp;
42                 }
43             }
44         }
45         if ( cost[len - 1] == INF ) cost[len - 1] = -1;
46         printf("%d\n", cost[len - 1]);
47     }
48     return 0;
49 }