[BOJ 3197] 백조의 호수

src/week3/BOJ3197/BOJ3197_V1.cpp

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+#include <bits/stdc++.h>
+using namespace std;
+queue<pair<int, int>> swan;
+queue<pair<int, int>> water;
+int day;
+int dy[4] = {0,0,1,-1};
+int dx[4] = {1,-1,0,0};
+int water_visited[1501][1501];
+int swan_visited[1501][1501];
+char lake_map[1501][1501];
+int main() {
+
+    int N,M;
+    cin >> M >> N;
+    bool swan_once = false;
+    for (int i=1; i<=M; i++) {
+        string s;
+        cin >> s;
+        for (int j=1; j<=N; j++) {
+            lake_map[i][j] = s[j-1];
+            if (lake_map[i][j] == 'L' && !swan_once) {
+                swan_once = true;
+                swan_visited[i][j] = 1;
+                swan.push({i, j});
+                lake_map[i][j] = '.';
+            } else if (lake_map[i][j] != 'X')
+            {
+                water.push({i,j});
+                water_visited[i][j] = 1;
+            }
+        }
+    }
+
+    while(true) {
+        queue<pair<int, int>> next_swan;
+        queue<pair<int, int>> next_water;
+
+        while(!swan.empty()) {
+            pair<int,int> curr_swan = swan.front();
+            swan.pop();
+
+            if (lake_map[curr_swan.first][curr_swan.second] == 'L') {
+                cout << day << '\n';
+                return 0;
+            }
+
+            for (int i=0; i<4; i++) {
+                int ny = curr_swan.first + dy[i];
+                int nx = curr_swan.second + dx[i];
+                if (ny < 1 || ny > M || nx < 1 || nx > N) continue;
+                if (swan_visited[ny][nx]) continue;
+
+                if (lake_map[ny][nx] == 'X') {
+                    next_swan.push(make_pair(ny, nx));
+                } else  {
+                    swan.push(make_pair(ny, nx));
+                }
+                swan_visited[ny][nx] = 1;
+            }
+        }
+
+        while(!water.empty()) {
+            pair<int, int> curr_water = water.front();
+            water.pop();
+
+            for (int i=0; i<4; i++) {
+                int ny = curr_water.first + dy[i];
+                int nx = curr_water.second + dx[i];
+                if (ny < 1 || ny > M || nx < 1 || nx > N) continue;
+                if (water_visited[ny][nx]) continue;
+                if (lake_map[ny][nx] == 'X') {
+                    next_water.push(make_pair(ny, nx));
+                    lake_map[ny][nx] = '.';
+                }
+                water_visited[ny][nx] = 1;
+            }
+        }
+
+        swan = next_swan;
+        water = next_water;
+        day++;
+    }
+
+
+
+    return 0;
+}