蓝桥杯2024年C++B组-数字接龙 题型：dfs

www.dotcpp.com/oj/problem3…

#include <iostream>
#include <cstring>
#include <algorithm>
#include <cstdio>
#include <vector>

using namespace std;

const int N = 15;


int n, k;
int g[N][N];
bool st[N][N];
int p[N][N];
vector<int> path;

int dx[8] = { -1, -1, 0, 1, 1, 1, 0, -1 };
int dy[8] = { 0, 1, 1, 1, 0, -1, -1, -1 };
bool dfs(int x, int y, int cnt)
{
	for (int i = 0; i < 8; ++i)
	{
		int tx = x + dx[i], ty = y + dy[i];
		if (tx < 0 || ty < 0 || tx >= n || ty >= n || st[tx][ty] || !(g[x][y] == k - 1 && g[tx][ty] == 0 || g[tx][ty] == g[x][y] + 1))
			continue;
		if (i == 1 && (p[x - 1][y] == 3 || p[x][y + 1] == 7))
			continue;
		if (i == 3 && (p[x][y + 1] == 5 || p[x + 1][y] == 1))
			continue;
		if (i == 5 && (p[x + 1][y] == 7 || p[x][y - 1] == 3))
			continue;
		if (i == 7 && (p[x][y - 1] == 1 || p[x - 1][y] == 5))
			continue;
		p[x][y] = i;
		st[tx][ty] = true;
		path.push_back(i);
		if (tx == n - 1 && ty == n - 1 && cnt == n * n - 1)
			return true;
		if (dfs(tx, ty, cnt + 1))
			return true;
		path.pop_back();
		st[tx][ty] = false;
		p[x][y] = -1;
	}

	return false;
}


void solve()
{
	 cin >> n >> k;

	 for (int i = 0; i < n; ++i)
		 for (int j = 0; j < n; ++j)
		 {
			 cin >> g[i][j];
			 p[i][j] = -1;
		 }

	if (g[0][0] != 0)
	{
		puts("-1");
		return;
	}

	st[0][0] = true;
	if (dfs(0, 0, 1))
	{
		for (auto x : path)
			cout << x;
		cout << endl;
	}
	else
		cout << -1 << endl;
}

int main()
{
	int t = 1;
	while (t--)
		solve();
}