ZOJ - 2477 dfs [kuangbin带你飞]专题二

注意输入的处理，旋转操作打表。递增枚举可能步数，作为限制方便找到最短路。

AC代码：90ms

#include<cstdio>
#include<cstring>

char magic[60];
int cube[6][9] = {
	{4,0,1,2,3,5,6,7,8},{22,9,10,11,21,23,33,34,35},{25,12,13,14,24,26,36,37,38},
    {28,15,16,17,27,29,39,40,41},{31,18,19,20,30,32,42,43,44},{49,45,46,47,48,50,51,52,53}
};
const int rot[12][20]={
         {11,23,35,34,33,21, 9,10,51,48,45,36,24,12, 6, 3, 0,20,32,44}, //只有20个需要改变，每个中心无需改变
         { 9,10,11,23,35,34,33,21,36,24,12, 6, 3, 0,20,32,44,51,48,45},
         {14,13,26,38,37,36,24,12,45,46,47,39,27,15, 8, 7, 6,11,23,35},
         {12,24,13,14,26,38,37,36,39,27,15, 8, 7, 6,11,23,35,45,46,47},
         {17,29,41,40,39,27,15,16,47,50,53,42,30,18, 2, 5, 8,14,26,38},
         {15,16,17,29,41,40,39,27,42,30,18, 2, 5, 8,14,26,38,47,50,53},
         {18,19,20,32,44,43,42,30,53,52,51,33,21, 9, 0, 1, 2,17,29,41},
         {42,30,18,19,20,32,44,43,33,21, 9, 0, 1, 2,17,29,41,53,52,51},
         { 0, 1, 2, 5, 8, 7, 6, 3,12,13,14,15,16,17,18,19,20, 9,10,11},
         { 6, 3, 0, 1, 2, 5, 8, 7,15,16,17,18,19,20, 9,10,11,12,13,14},
         {45,46,47,50,53,52,51,48,44,43,42,41,40,39,38,37,36,35,34,33},
         {51,48,45,46,47,50,53,52,41,40,39,38,37,36,35,34,33,44,43,42}
};

bool is_ok() {
	for(int i = 0; i < 6; ++i) {
		for(int j = 0; j < 8; ++j) {
			if(magic[cube[i][j]] != magic[cube[i][j+1]]) return false;
		}
	}
	return true;

}

void rotate(int k) { //旋转第k面
	int h = k ^ 1; //对应转动方式,顺时针or逆时针
	char tmp[60];
	memcpy(tmp, magic, sizeof(magic));
	for(int i = 0; i < 20; ++i) {
		magic[rot[k][i]] = tmp[rot[h][i]];
	}
}
int ans[2][10];
int limit;
int dfs(int cnt) {
	if(cnt >= limit) return is_ok();
	char old[60];
	memcpy(old, magic, sizeof(magic));
	for(int i = 0; i < 12; ++i) {
		rotate(i);
		ans[0][cnt] = i / 2;
		ans[1][cnt] = (i & 1) ? -1 : 1;
		if(dfs(cnt + 1)) return 1;
		memcpy(magic, old, sizeof(old));
	}
}

int main() {
	int T;
	scanf("%d", &T);
	char str[60];
	int kase = 0;
	while(T-- ) {
		if(kase++) getchar();
		for(int i = 0; i < 54; ++i) {
			while(1) {
				char ch = getchar();
				if(ch >= 'a' && ch <= 'z') {
					magic[i] = ch;
					break;
				}
			}
		}
		for(limit = 0; limit <= 6; ++limit) {
			if(limit == 6) printf("-1\n");
			else if(dfs(0)) {
				printf("%d\n", limit);
				for(int i = 0; i < limit; ++i) {
					printf("%d %d\n", ans[0][i], ans[1][i]);
				}
				break;
			}
		}
	}
	return 0;
}

如有不当之处欢迎指出！