[BOJ 4179] 불!

src/week3/BOJ4179/BOJ4179_V1.cpp

@@ -0,0 +1,90 @@
+#include <bits/stdc++.h>
+using namespace std;
+int N,M;
+int dy[4] = {0,0,1,-1};
+int dx[4] = {1,-1,0,0};
+int min_exit = INT_MAX;
+vector<vector<int>> inp_map;
+vector<vector<int>> fires_map;
+vector<vector<pair<int,int>>> fires;
+vector<vector<int>> visited;
+bool can_exit = false;
+void fire_flood(int level) {
+    for (int f=0; f<fires[level].size(); f++) {
+        int y = fires[level][f].first;
+        int x = fires[level][f].second;
+        fires_map[y][x] = 1;
+        for (int i=0; i<4; i++) {
+            int ny = y + dy[i];
+            int nx = x + dx[i];
+            if (ny >= 0 && nx >= 0 && ny < N && nx < M && inp_map[ny][nx] != 0 && inp_map[ny][nx] != 2) {
+                fires_map[ny][nx] = 1;
+                fires[level+1].push_back(make_pair(ny,nx));
+            }
+        }
+    }
+}
+void return_flood(int level) {
+    for (int f=0; f<fires[level].size(); f++) {
+        fires_map[fires[level][f].first][fires[level][f].second] = 0;
+    }
+}
+void dfs(int y, int x, int level) {
+    if (y == N-1 || x == M-1 || y == 0 || x == 0) {
+        can_exit = true;
+        min_exit = min(min_exit, level);
+        return;
+    }
+    visited[y][x] = 1;
+    fires.push_back(vector<pair<int,int>>());
+    fire_flood(level);
+    for (int i=0; i<4; i++) {
+        int ny = y + dy[i];
+        int nx = x + dx[i];
+        if (ny >= 0 && nx >= 0 && ny < N && nx < M && inp_map[ny][nx] != 0) {
+            if (inp_map[ny][nx] == 1 && visited[ny][nx] == 0) {
+                dfs(ny, nx, level+1);
+            }
+        }
+    }
+    return_flood(level+1);
+    fires.pop_back();
+
+}
+int main() {
+
+    ios_base::sync_with_stdio(false);
+    cin.tie(NULL);
+    cout.tie(NULL);
+    fires.push_back(vector<pair<int,int>>());
+    cin >> N;
+    cin >> M;
+    int sty, stx;
+    for (int i=0; i<N; i++) {
+        inp_map.push_back(vector<int>());
+        fires_map.push_back(vector<int>(M,0));
+        visited.push_back(vector<int>(M,0));
+        string temp;
+        cin >> temp;
+        for (int j=0; j<M; j++) {
+            if (temp[j] == '#')
+                inp_map[i].push_back(0);
+            else if (temp[j] == 'F') {
+                inp_map[i].push_back(2);
+                fires[0].push_back(make_pair(i,j));
+            } else if (temp[j] == 'J') {
+                inp_map[i].push_back(3);
+                sty = i, stx = j;
+            } else
+                inp_map[i].push_back(1);
+        }
+    }
+
+    dfs(sty,stx,0);
+    if (can_exit) cout << min_exit+1;
+    else cout << "IMPOSSIBLE";
+
+
+
+    return 0;
+}

src/week3/BOJ4179/BOJ4179_V2.cpp

@@ -0,0 +1,75 @@
+#include <bits/stdc++.h>
+using namespace std;
+int N,M;
+int dy[4] = {0,0,1,-1};
+int dx[4] = {1,-1,0,0};
+vector<vector<char>> inp_map;
+int fires[1004][1004];
+int human[1004][1004];
+queue<pair<int,int>> q;
+int ret, sty,stx;
+int max_val = INT_MAX;
+int main() {
+
+    cin >> N >> M;
+    fill(&fires[0][0], &fires[0][0] + 1004 * 1004, max_val);
+
+    for (int i = 0; i < N; i++) {
+        string s;
+        cin >> s;
+        inp_map.push_back(vector<char>());
+        for (int j = 0; j < M; j++) {
+            if (s[j] == 'J') {
+                inp_map[i].push_back(s[j]);
+                sty = i, stx = j;
+            } else if (s[j] == 'F') {
+                fires[i][j] = 1;
+                inp_map[i].push_back(s[j]);
+                q.push(make_pair(i,j));
+            } else {
+                inp_map[i].push_back(s[j]);
+            }
+        }
+    }
+
+    while(!q.empty()) {
+        int y, x;
+        tie(y,x) = q.front();
+        q.pop();
+        for (int i=0; i<4; i++) {
+            int ny = y+dy[i];
+            int nx = x+dx[i];
+            if (ny >= N || nx >= M || ny < 0 || nx < 0) continue;
+            if (fires[ny][nx] != max_val || inp_map[ny][nx] == '#') continue;
+            fires[ny][nx] = fires[y][x] + 1;
+            q.push(make_pair(ny,nx));
+        }
+    }
+
+    human[sty][stx] = 1;
+    q.push(make_pair(sty,stx));
+    while(!q.empty()) {
+        int y,x;
+        tie(y,x) = q.front();
+        q.pop();
+        if (y == N-1 || x == M-1 || y == 0 || x == 0) {
+            ret = human[y][x];
+            break;
+        }
+        for (int i=0; i<4; i++) {
+            int ny = y+dy[i];
+            int nx = x+dx[i];
+            if (ny >= N || nx >= M || ny < 0 || nx < 0) continue;
+            if (human[ny][nx] || inp_map[ny][nx] == '#') continue;
+            if (fires[ny][nx] <= human[y][x] + 1) continue;
+            human[ny][nx] = human[y][x] + 1;
+            q.push(make_pair(ny,nx));
+        }
+    }
+
+    if (ret == 0) cout << "IMPOSSIBLE";
+    else cout << ret;
+
+
+    return 0;
+}