每日算法 – day 22

每日算法

those times when you get up early and you work hard; those times when you stay up late and you work hard; those times when don’t feel like working — you’re too tired, you don’t want to push yourself — but you do it anyway. That is actually the dream. That’s the dream. It’s not the destination, it’s the journey. And if you guys can understand that, what you’ll see happen is that you won’t accomplish your dreams, your dreams won’t come true, something greater will. mamba out

那些你早出晚归付出的刻苦努力，你不想训练，当你觉的太累了但还是要咬牙坚持的时候，那就是在追逐梦想，不要在意终点有什么，要享受路途的过程，或许你不能成就梦想，但一定会有更伟大的事情随之而来。 mamba out~

2020.3.6

luogu- P1162 填涂颜色

广度优先搜索

#include <iostream>
#include <algorithm>
#include <cstdio>
#include <queue>

using namespace std;
const int N = 35;
int a[N][N], n ,dir[4][2] = {{1,0},{-1,0},{0,1},{0,-1}};
bool vis[N][N];


struct node{
    int x, y;
};

bool inmap(int x,int y)
{
    return x >= 0 && x <= n + 1 && y >= 0 && y <= n + 1;
}

void bfs(int x,int y)
{
    queue<node> q;
    q.push({x,y});
    vis[x][y] = 1;
    while(!q.empty())
    {
        node now = q.front();
        for(int i = 0;i < 4 ;i ++)
        {
            int nx = now.x + dir[i][0];
            int ny = now.y + dir[i][1];
            if(inmap(nx,ny) && a[nx][ny] != 1 && !vis[nx][ny])
            {
                vis[nx][ny] = 1;
                q.push({nx,ny});
            }
        }
        q.pop();
    }
}
int main()
{
    cin >> n;
    for(int i = 1;i <= n ;i ++)
    {
        for(int j = 1;j <= n ;j ++)
        {
            scanf("%d",&a[i][j]);
        }
    } 
    bfs(0,0);
    for(int i = 1;i <= n ;i ++)
    {
        for(int j = 1;j <= n ;j ++)
        {
            if(vis[i][j] == 0 && a[i][j] != 1)cout << "2 ";
            else cout << a[i][j] << " ";
        }
        cout << endl;
    }
    return 0;
}

P1141 01 迷宫

广度优先搜索 + 记忆化

#include <iostream>
#include <string>
#include <cstdio>
#include <algorithm>
#include <queue>
#include <vector>

using namespace std;
const int N = 1010;
int a[N][N], f[N][N], book[1000010][2], n, m;
bool vis[N][N];
int cnt = 0, dir[4][2] = { {1,0},{-1,0},{0,1},{0,-1} };
struct node {
    int x, y;
};

bool inmap(int x, int y)
{
    return x >= 1 && y >= 1 && x <= n && y <= n;
}

void bfs(int x, int y)
{
    vis[x][y] = 1;
    book[cnt][0] = x;
    book[cnt][1] = y;
    queue<node> q;
    q.push({ x,y });
    while (!q.empty())
    {
        node now = q.front();
        for (int i = 0; i < 4; i++)
        {
            int nx = now.x + dir[i][0];
            int ny = now.y + dir[i][1];
            if (inmap(nx, ny) && !vis[nx][ny] && a[now.x][now.y] != a[nx][ny])
            {
                cnt++;
                book[cnt][0] = nx;
                book[cnt][1] = ny;
                vis[nx][ny] = 1;
                q.push({ nx,ny });
            }
        }
        q.pop();
    }
}
int main()
{
    cin >> n >> m;
    string s;
    for (int i = 1; i <= n; i++)
    {
        cin >> s;
        for (int j = 0; j < s.size(); j++)
        {
            a[i][j + 1] = (s[j] == '1' ? 1 : 0);
        }
    }

    for (int i = 1; i <= n; i++)
    {
        for (int j = 1; j <= n; j++)
        {
            if (!vis[i][j])
            {
                cnt = 0;
                bfs(i, j);
                for (int k = 0; k <= cnt; k++)
                {
                    f[book[k][0]][book[k][1]] = cnt + 1;
                }
            }
        }
    }
    int a, b;
    for (int i = 0; i < m; i++)
    {
        scanf("%d %d", &a, &b);
        printf("%d\n", f[a][b]);
    }
    return 0;
}