标签：clu   dfs   namespace   any   family   VID   mit   iss   angular   

Oil Deposits

本题是指@表示油点，*表示非油点，油点相邻则表示一个油点而不是多个，找出总油点个数。没啥技巧，就是八个方向搜索，同时利用并查集的效率更高

DFS搜索：

#include <iostream>
#include <cstring>
using namespace std;
int m,n,many;
char s[105][105];
int visit[105][105];
const int dx[] = {0,0,1,1,1,-1,-1,-1};
const int dy[] = {1,-1,0,1,-1,0,1,-1};

void dfs(int i, int j){
    visit[i][j] = 1;
    for(int k = 0; k < 8; k++)
    {
        int nx = i + dx[k];
        int ny = j + dy[k];
        if(nx >= 0 && nx < m && ny >= 0 && ny < n && visit[nx][ny] == 0 && s[nx][ny] == ‘@‘)
            dfs(nx,ny);
    }
    //return 1;
} 

int main(){
    while(cin >> m >> n)
    {
        many = 0;
        memset(s, 0, sizeof(s));
        memset(visit,0,sizeof(visit));
        if(m == 0)
            break;
        for(int i = 0; i < m; i++){
            cin >> s[i];
        }    
        for(int i = 0; i < m; i++)
        {
            for(int j = 0; j < n; j++)
            {
                if(s[i][j] == ‘@‘ && visit[i][j] == 0)
                {
                    many++;
                    dfs(i, j);
                }
                
            }
        }
        cout << many << endl;
    }
    return 0;
}

并查集:

#include<bits/stdc++.h>
using namespace std;
char g[101][101];
int fa[101 * 101];
int x[] = { 0,0,1,-1,1,-1,1,-1 };
int y[] = { 1,-1,0,0,1,1,-1,-1 };
int n, m;
int id(int x, int y) {
    return (x - 1)*m + y;
}
bool isok(int x, int y) {
    if (0 < x&&x <= n && 0 < y&&y <= m)
        return true;
    return false;
}
int Find(int x) {
    return fa[x] == x ? x : fa[x] = Find(fa[x]);
}

int vis[101 * 101];
int main() {
    while (scanf("%d%d", &n, &m) != EOF && n + m) {
        memset(vis, 0, sizeof vis);
        for (int i = 1; i <= n; ++i) {
            for (int j = 1; j <= m; ++j) {
                fa[id(i, j)] = id(i, j);
            }
        }
        for (int i = 1; i <= n; ++i)
            scanf("%s", g[i] + 1);
        for (int i = 1; i <= n; ++i) {
            for (int j = 1; j <= m; ++j) {
                if (g[i][j] == ‘*‘) continue;
                for (int k = 0; k < 7; ++k) {
                    int xx = i + x[k], yy = j + y[k];
                    if (isok(xx, yy) == false || g[xx][yy] == ‘*‘) continue;
                    int f1 = Find(id(i, j)), f2 = Find(id(xx, yy));
                    if (f1 != f2) {
                        fa[f1] = f2;
                    }
                }
            }
        }
        int cnt = 0;
        for (int i = 1; i <= n; ++i) {
            for (int j = 1; j <= m; ++j) {
                if (g[i][j] != ‘*‘&&vis[Find(id(i, j))] == 0) {
                    cnt++;
                    vis[Find(id(i, j))] = 1;
                }
            }
        }
        cout << cnt << endl;
    }

    return 0;
}

#1241： Oil Deposits（八向搜索 + 并查集）

标签：clu   dfs   namespace   any   family   VID   mit   iss   angular   

原文地址：https://www.cnblogs.com/RioTian/p/12858317.html