[IDA*] UVa1343 The Rotation Game 旋转游戏

代码

#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <algorithm>
using namespace std;

/*
0         1
2         3
4     5    6    7    8    9    10
11        12
13  14  15  16   17   18   19
20         21
22         23
*/

const int mymove[8][7] = {
{0,2,6,11,15,20,22},
{1,3,7,12,16,21,23},
{10,9,8,7,6,5,4},
{19,18,17,16,15,14,13},
{23,21,16,12,7,3,1},
{22,20,15,11,6,2,0},
{13,14,15,16,17,18,19},
{4,5,6,7,8,9,10}
};

const int myrev[8] = { 5,4,7,6,1,0,3,2 };
const int center[8] = { 6,7,8,12,17,16,15,11 };

const int maxn = 24;
const int maxans = 100;
int A[24], ans[maxans];

bool finaled() {
for (int i = 1; i < 8; i++)
if (A[center[i]] != A[center[0]]) return false;
return true;
}

int diff(int v) {
int ans = 0;
for (int i = 0; i < 8; i++)
if (A[center[i]] != v) ans++;
return ans;
}

int h() {
return min(min(diff(1), diff(2)), diff(3));
}

bool dfs(int d, int maxd) {
if (finaled()) return true;
if (d >= maxd) return false;
if (d + h() > maxd) return false;

for (int i = 0; i < 8; i++) {
int temp = A[mymove[i][0]];
for (int j = 0; j < 6; j++)
A[mymove[i][j]] = A[mymove[i][j + 1]];
A[mymove[i][6]] = temp;
ans[d] = i;
if (dfs(d + 1, maxd)) return true;

temp = A[mymove[myrev[i]][0]];
for (int j = 0; j < 6; j++)
A[mymove[myrev[i]][j]] = A[mymove[myrev[i]][j + 1]];
A[mymove[myrev[i]][6]] = temp;
}

return false;
}

int main() {
while (scanf("%d", &A[0]) == 1 && A[0]) {
for (int i = 1; i < maxn; i++) scanf("%d", &A[i]);
memset(ans, 0, sizeof(ans));
int maxd;
for (maxd = 0; maxd < maxans; maxd++) {
if (dfs(0, maxd)) break;
}
if (!maxd) printf("No moves needed\n");
else {
for (int i = 0; i < maxd; i++)
printf("%c", ans[i] + 'A');
printf("\n");
}
printf("%d\n", A[6]);
}
return 0;
}

体会

测评的时候还是WA，实在找不到是哪个点有问题，算了很多样例没问题吧大概，就先发上来了。

好简单的IDA*, 剪枝条件为 maxd <= h() + d()，其中此题的h()很好算，就是中间那一块，不统一的数字个数（说不清，看代码），因为每次移动顶多只能改变一个不统一数字咯。