状态:d[i][j]表示第i个立方体第j个面朝上时塔的最大高度。
状态转移:dp[i][j] = max{dp[k][l]]+1|a[i][j^1]==a[k][l]};
输出路径用一个next数组记录下就可以了。
代码如下:
#include <cstdio> #include <cstring> #define N 505 char ans[6][10] = {"front", "back", "left", "right", "top", "bottom"}; int n, a[N][6], next[N][6][2], d[N][6], flag; void print_ans(int x, int y, int cur) { if(cur==0) return; printf("%d %s\n", x, ans[y]); print_ans(next[x][y][0],next[x][y][1],cur-1); } int main () { int cas = 0; while(scanf("%d",&n),n) { for(int i = 1; i <= n; i++) for(int j = 0; j < 6; j++) scanf("%d",&a[i][j]); for(int i = 0; i < 6; i++) d[n][i] = 1; int maxi, maxj, max = 1; for(int i = n-1; i >=1 ; i--) { for(int j = 0; j < 6; j++) { int &ans = d[i][j]; int ansi, ansj; ans = 1; for(int k = n; k > i; k--) for(int l = 0; l < 6; l++) if(a[i][j^1]==a[k][l]&&ans<d[k][l]+1) { ans = d[k][l]+1; ansi = k; ansj = l; } next[i][j][0] = ansi; next[i][j][1] = ansj; if(max<d[i][j]) { max = d[i][j]; maxi = i; maxj = j; } } } flag = max; if(cas) printf("\n"); printf("Case #%d\n%d\n",++cas,max); print_ans(maxi,maxj,max); } return 0; }