题目链接：
题目分析：
启发式搜索入门经典题
- 迭代加深：
本题最大次数15次，超过15次直接return - 估价函数：
当前走的次数和与答案的偏差值，超过16直接return
代码：
#include <bits/stdc++.h>
using namespace std;
inline int read() {
int cnt = 0, f = 1; char c = getchar();
while (!isdigit(c)) {if (c == '-') f = -f; c = getchar();}
while (isdigit(c)) {cnt = (cnt << 3) + (cnt << 1) + c - '0'; c = getchar();}
return cnt * f;
}
const char check[10][10] =
{{'1', '1', '1', '1', '1'},
{'0', '1', '1', '1', '1'},
{'0', '0', '*', '1', '1'},
{'0', '0', '0', '0', '1'},
{'0', '0', '0', '0', '0'}};
const int dx[10] = {1, -1, 1, -1, 2, -2, 2, -2};
const int dy[10] = {2, -2, -2, 2, 1, -1, -1, 1};
char mapp[10][10];
int T, ans;
int spacex, spacey;
int test() {
int tot = 0;
for (register int i = 0; i < 5; i++)
for (register int j = 0; j < 5; j++)
if (mapp[i][j] != check[i][j]) ++tot;
// cout<<tot<<endl;
return tot;
}
void dfs_(int cnt, int x, int y, int lastx, int lasty) {
// cout<<x<<" "<<y<<endl;
if (cnt + test() > 16) return;
if (cnt >= ans) return;
if (!test()) {ans = min(ans, cnt); return;}
for (register int i = 0; i <= 7; ++i) {
if (x + dx[i] < 0 || x + dx[i] > 4) continue;
if (y + dy[i] < 0 || y + dy[i] > 4) continue;
if (x + dx[i] == lastx && y + dy[i] == lasty) continue;
swap(mapp[x + dx[i]][y + dy[i]], mapp[x][y]);
dfs_(cnt + 1, x + dx[i], y + dy[i], x, y);
swap(mapp[x + dx[i]][y + dy[i]], mapp[x][y]);
}
}
int main() {
T = read();
while (T--) {
ans = 10000;
memset(mapp, 0, sizeof(mapp));
for (register int i = 0; i < 5; ++i) scanf("%s", mapp[i]);
for (register int i = 0; i < 5; ++i)
for (register int j = 0; j < 5; ++j)
if (mapp[i][j] == '*') spacex = i, spacey = j;
dfs_(0, spacex, spacey, -1, -1);
ans == 10000 ? printf("-1
") : printf("%d
", ans);
}
return 0;
}