第18组题解

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#include <iostream>
#include <cstring>
using namespace std;
const int maxn = 10;
bool bol[maxn];
char maps[maxn][maxn];
int n, k, cnt, way;
void dfs(int h)
{
	if(cnt == k)
	{
		way++;
		return ;
	}
	if(h >= n)
		return ;
	for(int i = 0; i < n; i++)
	{
		if(!bol[i] && maps[h][i] == '#')
		{
			cnt++;
			bol[i] = true;
			dfs(h + 1);
			cnt--;			//dfs 初始化操作 
			bol[i] = false;
		}
	}
	dfs(h + 1); 
}
int main()
{
	while(1)
	{
		way = 0;
		cnt = 0;
		memset(bol, false, sizeof bol);
		cin >> n >> k;
		if(n == -1 && k == -1)
			break;
		int i, j;
		for(i = 0; i < n; i++)
		{
			for(j = 0; j < n; j++)
			{
				cin >> maps[i][j];
			}
		}
		dfs(0);
		cout << way << endl;
	}
	
	return 0;
}

#include <iostream>
#include <cmath>
using namespace std;

int n, a = 1, b = 0, ans = 0x3f3f3f3f;
int S[20];
int B[20];
bool vis[20];

void dfs(int x)
{
	if(x > n)
		return ;
	else
	{
		for(int i = 1; i <= n; i++)
		{
			if(!vis[i])
			{
				a *= S[i];
				b += B[i];
				vis[i] = 1;
				ans = min(ans, abs(a - b));
				dfs(i + 1);
				vis[i] = 0;
				a /= S[i];
				b -= B[i];
			}
		}
	}
}
int main()
{
	cin >> n;
	for(int i = 1; i <= n; i++)
	{
		cin >> S[i] >> B[i];
	}
	dfs(1);
	cout << ans << endl;
	return 0;
}

#include <iostream>
#include <algorithm>
#include <cstring> 
using namespace std;
const int maxn = 10;
char str[maxn];
int main()
{
	cin >> str;
	int n = strlen(str);
	do
	{
		cout << str << endl;
	}
	while(next_permutation(str, str + n));
	return 0;
}

#include <iostream>
using namespace std;

int n, a[30];

void pr(int x)
{
	cout << n << '=';
	for(int i = 1; i < x - 1; i++)
	{
		cout << a[i] << '+';
	}
	cout << a[x - 1] << endl;
}

void dfs(int x, int y)   // x 表示 第几个盒子，y表示当前数字还剩多少 
{
	if(y == 0 && x > 2) // 01 - 为什么 x > 2 至少拆一次 即x > 1 但默认会x + 1 所以 x > 2 
	{
		pr(x); 
		return ; 
	}
	for(int i = 1; i <= y; i++)
	{
		if(i >= a[x - 1]) // 后面的数字要大于等于前面的数字 
		{
			a[x] = i;
			y -= i;
			dfs(x + 1, y);
			a[x] = 0;
			y += i;
		}
	}
}

int main()
{
	cin >> n;
	a[0] = 1;
	dfs(1, n); 
	return 0;
}

#include <iostream>
#include <cmath>
#include <cstring>
#include <cstdio>
using namespace std;

int n;
int ans[40];
bool vis[40];

void pr()
{
	for(int i = 1; i <= n - 1; i++)
	{
		cout << ans[i] << ' ';
	}
	cout << ans[n] << endl;
}

bool isPrime(int x)
{
	bool flag = true;
	for(int i = 2; i <= sqrt(x); i++)
	{
		if(x % i == 0)
			flag = false;
	}
	return flag;
}

void dfs(int step)
{
	if(step > n && isPrime(ans[1] + ans[n]))
	{
		pr();
		return ;
	}
	for(int i = 2; i <= n; i++)
	{
		ans[step] = i;
		if(vis[i] || isPrime(ans[step] + ans[step - 1]) == 0)
			continue;
		vis[i] = 1;
		dfs(step + 1);
		vis[i] = 0;
	}
}

int main()
{
	int j = 1;
	while(cin >> n)
	{
		if(j >= 2)
			cout << endl;
		memset(ans, 0, sizeof ans);
		memset(vis, 0, sizeof vis);
		printf("Case %d:\n", j);
		j++;
		vis[1] = 1;
		ans[1] = 1;
		dfs(2);
	}
	return 0;
}

#include <iostream>
#include <cstring>

using namespace std;
int n, m, way, sx, sy;
char a[30][30];
bool map[30][30];
bool vis[30][30];
int xx[ ] = {0, 0, -1, 1};
int yy[ ] = {1, -1, 0, 0};

void dfs(int x, int y)
{
	for(int i = 0; i < 4; i++)
	{
		int dx = x + xx[i];
		int dy = y + yy[i];
		if(map[dx][dy] || vis[dx][dy] || dx < 1 || dx > n || dy < 1 || dy > m)
			continue;
		way++;
		vis[dx][dy] = 1;
		dfs(dx, dy);
//		vis[dx][dy] = 0; // 不回溯 
	}
}

int main()
{
	while(1)
	{
		way = 1;
		cin >> m >> n;
		if(m == 0 && n == 0)
			break;
		memset(a, '\0', sizeof a); 
		memset(map, false, sizeof map);
		memset(vis, false, sizeof vis);
		for(int i = 1; i <= n; i++)
		{
			for(int j = 1; j <= m; j++)
			{
				cin >> a[i][j];
				if(a[i][j] == '#')
					map[i][j] = true;
				if(a[i][j] == '@')
				{
					sx = i;
					sy = j;
				}
			}
		}
		vis[sx][sy] = 1;
		dfs(sx, sy);
		cout << way << endl;
	}
	return 0;
}

#include <bits/stdc++.h>
#define MAXN 305

using namespace std;

int sx, sy, ex, ey, l;
bool vis[MAXN][MAXN];
int moves[8][2] = {{-2, -1}, {-1, 2}, {1, 2}, {2, 1}, {2, -1}, {1, -2}, {-1, -2}, {-2, -1}};
struct node
{
	int x;
	int y;
	int step;
} p[1000050];

void bfs()
{
	memset(vis, false, sizeof vis);
	vis[sx][sy] = 1;
	int head = 1, tail = 1;
	p[tail].x = sx;
	p[tail].y = sy;
	p[tail].step = 0;
	tail++;
	while(head < tail)
	{
		int x = p[head].x;
		int y = p[head].y;
		int step = p[head].step; 
		if(x == ex && y== ey)
		{
			cout << step << endl;
			return ;
		}
		for(int i = 0; i < 8; i++)
		{
			int nx = x + moves[i][0];
			int ny = y + moves[i][1];
			if(nx >= 0 && nx < l && ny >= 0 && ny < l && vis[nx][ny] == 0) 
			{
				vis[nx][ny] = 1;
				p[tail].x = nx;
				p[tail].y = ny;
				p[tail].step = step + 1;
				tail++;
			} 
		} 
		head++;
	}
}

int main()
{
	int n;
	cin >> n;
	while(n--)
	{
		cin >> l >> sx >> sy >> ex >> ey;
		bfs();
	}
	return 0;
}

#include <iostream>

using namespace std;

int n, m, way; 
bool vis[200][200];
char map[200][200];
int moves[8][2] = {{1, 0}, {1, -1}, {0, -1}, {-1, -1}, {-1, 0}, {-1, 1}, {0, 1}, {1, 1}};

void dfs(int x, int y)
{
	map[x][y] = '*';
	for(int i = 0; i < 8; i++)
	{
		int dx = x + moves[i][0], dy = y + moves[i][1];
		if(map[dx][dy] == '@' && dx >= 0 && dx <= n && dy >= 0 && dy <= m)
			dfs(dx, dy);
	}
}

int main()
{
	int i, j, k = 0;
	int u, v;
	char ch;
	while(cin >> n >> m)
	{
		int ans = 0;
		if(n == 0 && m == 0)
			break;
		for(i = 1; i <= n; i++)
		{
			for(j = 1; j <= m; j++)
			{
				cin >> map[i][j];
			}
		}
		for(i = 1; i <= n; i++)
		{
			for(j = 1; j <= m; j++)
			{
				if(map[i][j] == '@')
				{
					dfs(i, j);
					ans++;
				}
			}
		}
		cout << ans << endl;
	}
	return 0;
}

#include <iostream>

using namespace std;

int n, m, way;
char map[150][150];
bool vis[150][150];
int moves[8][2] = {{1, 0}, {1, -1}, {0, -1}, {-1, -1}, {-1, 0}, {-1, 1}, {0, 1}, {1, 1}};

void dfs(int x, int y)
{
	map[x][y] = '.';
	for(int i = 0; i < 8; i++)
	{
		int dx = x + moves[i][0];
		int dy = y + moves[i][1];
		if(map[dx][dy] == 'W' && dx <= n && dx >= 1 && dy <= m && dy >= 1)
		{
			vis[dx][dy] = 1;
			dfs(dx, dy);
		}
	}
}

int main()
{
	int ans = 0;
	cin >> n >> m;
	for(int i = 1; i <= n; i++)
	{
		for(int j = 1; j <= m; j++)
		{
			cin >> map[i][j];
		}
	}
	for(int i = 1; i <= n; i++)
	{
		for(int j = 1; j <= m; j++)
		{
			if(map[i][j] == 'W')
			{
				dfs(i, j);
				ans++;
			}
		}
	}
	cout << ans << endl;
	return 0;
}

#include<bits/stdc++.h>
using namespace std;
struct p{
	int l;
	int r;
}t[100010];
void dfs(int x){
	if(x==0)
	return;
	cout<<x<<endl;//第1步
	dfs(t[x].l);//第2步
	dfs(t[x].r);//第3步
}
int main()
{
	int n;
	cin>>n;
	for(int i=1;i<=n;i++)
		cin>>t[i].l>>t[i].r;//依次读入左右节点
	dfs(1);
	return 0;
}

#include <iostream>
using namespace std;

int n, m, sx, sy, tx, ty, flag = 0;
char map[20][20];
bool vis[20][20];
bool wal[20][20];

int xx[] = {1,0,-1,0};
int yy[] = {0,-1,0,1};

void dfs(int x,int y)
{
	if(x == tx && y == ty)
	{
		flag = 1;
		return ;
	}
	for(int i = 0; i < 4; i++)
	{
		int dx = x + xx[i];
		int dy = y + yy[i];
		if(dx >= 1 && dx <= n && dy >= 1 && dy <= m && !vis[dx][dy] && !wal[dx][dy])
		{
			vis[dx][dy] = 1;
			dfs(dx, dy);
			vis[dx][dy] = 0;
		}
	}
}

int main()
{
	cin >> n >> m;
	for(int i = 1; i <= n; i++)
	{
		for(int j = 1; j <= m; j++)
		{
			cin >> map[i][j];
			if(map[i][j] == '*')
				wal[i][j] = 1;
			if(map[i][j] == 'S')
				sx = i, sy = j;
			if(map[i][j] == 'T')
				tx = i, ty = j;	
		} 
	}
	vis[sx][sy] = 1;
	dfs(sx, sy);
	if(flag == 0)
		cout << "no" << endl;
	else
		cout << "yes" << endl;
	return 0;
}

#include <iostream>
#include <cstring>

using namespace std;

int t, n, m, x, y, ans = 0;
int xx[ ] = {-2, -1, 1, 2, 2, 1, -1, -2};
int yy[ ] = {1, 2, 2, 1, -1, -2, -2, -1};
bool vis[10][10];

void dfs(int x, int y, int step)
{
	if(step == n * m)
	{
		ans++;
		return ;
	}
	else
	{
		for(int i = 0; i < 8; i++)
		{
			int dx = x + xx[i];
			int dy = y + yy[i];
			if(vis[dx][dy] || dx < 0 || dx >= n || dy < 0 || dy >= m)
				continue;
			vis[dx][dy] = 1;
			dfs(dx, dy, step + 1);
			vis[dx][dy] = 0;
		}
	}
}

int main()
{
	cin >> t;
	while(t--)
	{
		ans = 0;
		memset(vis, false, sizeof vis);
		cin >> n >> m >> x >> y;
		vis[x][y] = 1;
		dfs(x, y, 1);
		cout << ans << endl;
	}
	
	return 0;
}

#include<bits/stdc++.h>
using namespace std;
const int n = 8;
int tmp, ans;
int x[10];
int chess[10][10];
bool no(int r, int c) {//判断两个皇后的坐标是否冲突
	for (int i = 0; i < r; i++) {
		if (x[i] == c || abs(r - i) == abs(c - x[i])) 
		return false;
	}
	return true;
}
void queen(int k) {
	if (k == n) { 
	ans = max(ans, tmp);//找所有情况的八皇后的最大权值和
	return;
	}
	for (int i = 0; i < n; i++) {
		if (no(k, i)) {
			x[k] = i;//dfs前做好标记
			tmp += chess[k][i];
			queen(k + 1);
			x[k] = 0;//dfs后删除标记
			tmp -= chess[k][i];
		}
	}
}
int main() 
{
	int t;
	scanf("%d", &t);
	while (t--) {
		tmp = ans = 0;
		memset(x, 0, sizeof(x));
		for (int i = 0; i < n; i++) {
			for (int j = 0; j < n; j++)
				scanf("%d", &chess[i][j]);
		}
		queen(0);
		printf("%d\n", ans);
	}
	return 0;
}

#include <iostream>
#include <cmath>

using namespace std;
int ans, m, n, k, a[30];

bool isPrime(int x)
{
	int i;
	for(i = 2; i <= sqrt(x); i++)
	{
		if(x % i == 0)
			return 0;
	}	
	return 1;
}

void dfs(int m, int sum, int j)
{
	if(m == k)
	{
		if(isPrime(sum))
			ans++;
		return ;
	}
	for(int i = j; i < n; i++)
	{
		dfs(m + 1,sum + a[i], i + 1);
	}
	return ;
}

int main()
{
	cin >> n >> k;
	for(int i = 0; i < n; i++)
	{
		cin >> a[i];
	}
	dfs(0, 0, 0);
	cout << ans << endl;
	return 0;
}

#include<bits/stdc++.h>
using namespace std;
#define fir(i,a,b) for(int i=a;i<=b;i++)
const int N=510;
const int dxy1[4][2]= {{1,1},{-1,-1},{1,-1},{-1,1}},dxy2[4][2]= {{1,1},{0,0},{1,0},{0,1}};
struct node
{
    int x,y;
};
int t,n,m,ans=1e8,dis[N][N];
char s[N][N];
bool vis[N][N];
deque<node> q;
int check(int x,int y)
{
    return x>=0 && x<=n && y>=0 && y<=m;
}
void bfs()
{
    vis[0][0]=1;
    memset(vis,0,sizeof(vis));
    memset(dis,0x3f,sizeof(dis));
    q.push_front(node {0,0});
    dis[0][0]=0;
    while(q.size())
    {
        node now=q.front();
        q.pop_front();
        fir(i,0,3)
        {
            int tx=now.x+dxy1[i][0],t1=now.x+dxy2[i][0];
            int ty=now.y+dxy1[i][1],t2=now.y+dxy2[i][1];
            int tt=(s[t1][t2] != (i<=1? '\\':'/'));
            if(check(tx,ty) && dis[tx][ty]>dis[now.x][now.y]+tt)
            {
                dis[tx][ty]=dis[now.x][now.y]+tt;
                if(tt)
                    q.push_back(node {tx,ty});
                else
                    q.push_front(node {tx,ty});
            }
        }
    }
}
int main()
{
        cin>>n>>m;
        fir(i,1,n)
        fir(j,1,m)
        cin>>s[i][j];
        bfs();
        if(dis[n][m]<1e8)
            cout<<dis[n][m]<<endl;
        else
            cout<<"NO SOLUTION"<<endl;
    return 0;
}