[트리] 1976244 유영민

08_DFS & BFS/도전/1844.cpp

@@ -0,0 +1,45 @@
+#include <vector>
+#include <queue>
+#include <iostream>
+using namespace std;
+typedef pair<int, int> pi;
+//
+int solution(vector<vector<int>> maps)
+{
+    int answer = 0;
+    int dr[] = {-1, 0, 1, 0};
+    int dc[] = {0, 1, 0, -1};
+    int n = maps.size();
+    int m = maps[0].size();
+
+    // 시작점 0,0에서 BFS 실행
+    queue<pi> q;
+    q.push({0, 0});
+    while (!q.empty())
+    {
+        int r = q.front().first;
+        int c = q.front().second;
+        q.pop();
+
+        for (int k = 0; k < 4; k++)
+        {
+            int nr = r + dr[k];
+            int nc = c + dc[k];
+            if (nr < n && nr >= 0 && nc < m && nc >= 0 && maps[nr][nc] == 1)
+            {
+                maps[nr][nc] = maps[r][c] + 1;
+                q.push({nr, nc});
+            }
+        }
+    }
+
+    if (maps[n - 1][m - 1] == 1)
+    {
+        answer = -1;
+    }
+    else
+    {
+        answer = maps[n - 1][m - 1];
+    }
+    return answer;
+}

08_DFS & BFS/도전/19538.cpp

@@ -0,0 +1,93 @@
+#include <iostream>
+#include <vector>
+#include <queue>
+
+using namespace std;
+
+// BFS
+vector<int> tookMin(vector<int> &rumor_mongers, int n, vector<vector<int>> &nbr_graph)
+{
+    int cnt = 0;
+    queue<int> gossip;
+    queue<int> influenced;
+
+    // 모두 처음에는 안 믿는다.
+    vector<int> believed(n + 1, -1);
+    vector<int> cnt_nbr_believers(n + 1, 0);
+
+    // 유포자를 큐에 넣는다 (0으로 셋팅)
+    for (int rm : rumor_mongers)
+    {
+        believed[rm] = 0;
+        gossip.push(rm);
+    }
+
+    // 루머 유포 시작
+    while (!gossip.empty())
+    {
+        cnt++;
+        int node = gossip.front();
+        gossip.pop();
+
+        for (int j = 0; j < nbr_graph[node].size(); j++)
+        {
+            int next_node = nbr_graph[node][j];
+            // 안 믿는 사람이지만, 여론에 따라 믿게 되는 경우
+            if (believed[next_node] == -1 && ++cnt_nbr_believers[next_node] >= (nbr_graph[next_node].size() + 1) / 2)
+            {
+                influenced.push(next_node);
+                gossip.push(next_node);
+            }
+        }
+
+        // node에 의해 영향 받은 사람들이 동시에 믿게 된다.
+        while (!influenced.empty())
+        {
+            believed[influenced.front()] = believed[node] + 1;
+            influenced.pop();
+        }
+    }
+    cout << cnt << "*\n";
+    return believed;
+}
+
+int main()
+{
+    ios_base::sync_with_stdio(false);
+    cin.tie(NULL);
+    cout.tie(NULL);
+
+    // 입력
+    int n, m, nbr, rumor_monger;
+    cin >> n;
+    vector<vector<int>> nbr_graph(n + 1);
+    vector<int> rumor_mongers;
+
+    for (int i = 1; i <= n; i++)
+    {
+        while (true)
+        {
+            cin >> nbr;
+            if (!nbr)
+            {
+                break;
+            }
+            nbr_graph[i].push_back(nbr);
+        }
+    }
+    cin >> m;
+    while (m--)
+    {
+        cin >> rumor_monger;
+        rumor_mongers.push_back(rumor_monger);
+    }
+
+    // 계산
+    vector<int> ans = tookMin(rumor_mongers, n, nbr_graph);
+
+    // 출력
+    for (int i = 1; i <= n; i++)
+    {
+        cout << ans[i] << ' ';
+    }
+}

08_DFS & BFS/필수/1325.cpp

@@ -0,0 +1,75 @@
+#include <iostream>
+#include <vector>
+#include <stack>
+
+using namespace std;
+
+vector<int> mostEfficientHack(vector<vector<int>> &relate, int n)
+{
+    vector<int> ans;
+    int max_cnt = 0;
+
+    // 1부터 n번 컴퓨터까지 다 시작해본다. (브루트 포스)
+    for (int i = 1; i <= n; i++)
+    {
+        stack<int> s;
+        vector<bool> visited(n + 1, false);
+
+        s.push(i);
+        visited[i] = true;
+        int cnt = 1;
+        while (!s.empty())
+        {
+            int node = s.top();
+            s.pop();
+
+            for (int j = 0; j < relate[node].size(); j++)
+            {
+                int next_node = relate[node][j];
+                if (!visited[next_node])
+                {
+                    // 해킹된 컴퓨터 있을때마다 count
+                    visited[next_node] = true;
+                    cnt++;
+                    s.push(next_node);
+                }
+            }
+        }
+        // 최종 cnt로 max 업데이트 및 새로운 list
+        if (cnt > max_cnt)
+        {
+            max_cnt = cnt;
+            ans.resize(0);
+            ans.push_back(i);
+        }
+        else if (cnt == max_cnt)
+        {
+            ans.push_back(i);
+        }
+    }
+    return ans;
+}
+
+int main()
+{
+    ios_base::sync_with_stdio(false);
+    cin.tie(NULL);
+    cout.tie(NULL);
+
+    int n, m, a, b;
+    cin >> n >> m;
+    vector<vector<int>> relate(n + 1);
+
+    while (m--)
+    {
+        cin >> a >> b;
+        relate[b].push_back(a);
+    }
+
+    vector<int> ans = mostEfficientHack(relate, n);
+
+    for (int comp : ans)
+    {
+        cout << comp << ' ';
+    }
+}

08_DFS & BFS/필수/2615.cpp

@@ -0,0 +1,64 @@
+#include <iostream>
+#include <vector>
+
+using namespace std;
+
+vector<vector<int>> board(19, vector<int>(19, 0));
+int dr[] = {1, 1, 1, 0, 0, -1, -1, -1};
+int dc[] = {-1, 0, 1, -1, 1, -1, 0, 1};
+
+// 같은 방향으로 계속 전진하다가 다른 숫자 만나면 or 바둑판 범위 넘어가면 depth 리턴
+int inARow(int i, int d, int r, int c, int color)
+{
+    if (r < 0 || r >= 19 || c < 0 || c >= 19 || board[r][c] != color)
+    {
+        return d;
+    }
+
+    int nr = r + dr[i];
+    int nc = c + dc[i];
+
+    return inARow(i, d + 1, nr, nc, color);
+}
+
+int main()
+{
+
+    for (int r = 0; r < 19; r++)
+    {
+        for (int c = 0; c < 19; c++)
+        {
+            cin >> board[r][c];
+        }
+    }
+
+    for (int r = 0; r < 19; r++)
+    {
+        for (int c = 0; c < 19; c++)
+        {
+            if (!board[r][c])
+            {
+                continue;
+            }
+
+            for (int i = 0; i < 8; i++)
+            {
+                // 리턴했을때 연속depth가 5였으면 승리!!     //양방향 고려해줌                     //양방향이므로 교집합 하나 빼줌
+                if (5 == inARow(i, 0, r, c, board[r][c]) + inARow(7 - i, 0, r, c, board[r][c]) - 1)
+                {
+                    // 밑에서 왼쪽 방향으로 가는 경우에만 시작점이 최대왼쪽이 아니라서, 업데이트해줘야함
+                    if (i == 0)
+                    {
+                        r += 4;
+                        c -= 4;
+                    }
+                    cout << board[r][c] << '\n';
+                    cout << r + 1 << ' ' << c + 1;
+                    return 0;
+                }
+            }
+        }
+    }
+
+    cout << '0';
+}

08_DFS & BFS/필수/4963.cpp

@@ -0,0 +1,85 @@
+#include <iostream>
+#include <vector>
+#include <queue>
+
+using namespace std;
+
+typedef pair<int, int> pi;
+int dr[] = {-1, -1, -1, 0, 0, 1, 1, 1};
+int dc[] = {-1, 0, 1, -1, 1, -1, 0, 1};
+
+// bfs를 통한 섬 개수 세기
+
+int cntIsland(vector<vector<int>> &map, int h, int w)
+{
+    // 미개척 땅이 1이므로 2부터 셈
+    int cnt = 1;
+    queue<pi> ut;
+
+    // cout << "^__^";
+
+    for (int i = 0; i < h; i++)
+    {
+        for (int j = 0; j < w; j++)
+        {
+            // 개척 안한 땅 발견하면 "새 섬이다!"
+            if (map[i][j] == 1)
+            {
+                cnt++;
+                map[i][j] = cnt;
+                ut.push({i, j});
+
+                // 해당 섬 끝까지 마킹
+                while (!ut.empty())
+                {
+                    pi land = ut.front();
+                    ut.pop();
+
+                    for (int k = 0; k < 8; k++)
+                    {
+                        int nr = land.first + dr[k];
+                        int nc = land.second + dc[k];
+
+                        if (nr >= 0 && nr < h && nc >= 0 && nc < w && map[nr][nc] == 1)
+                        {
+                            map[nr][nc] = cnt;
+                            ut.push({nr, nc});
+                        }
+                    }
+                }
+
+            }
+        }
+    }
+    return --cnt;
+}
+
+int main()
+{
+    ios_base::sync_with_stdio(false);
+    cin.tie(NULL);
+    cout.tie(NULL);
+
+    int w, h;
+
+    while (true)
+    {
+        cin >> w >> h;
+        if (!w && !h)
+        {
+            break;
+        }
+
+        vector<vector<int>> map(h, vector<int>(w, 0));
+
+        for (int i = 0; i < h; i++)
+        {
+            for (int j = 0; j < w; j++)
+            {
+                cin >> map[i][j];
+            }
+        }
+
+        cout << cntIsland(map, h, w) << '\n';
+    }
+}