Create wyspy.cpp

src/cw9/zad9/wyspy.cpp

@@ -0,0 +1,66 @@
+#include <bits/stdc++.h>
+using namespace std;
+
+const int dx[]={0, 0, 1, -1};
+const int dy[]={-1, 1, 0, 0};
+
+bool ok(int y, int x, int n, int m){
+	return x>=0&&x<m&&y>=0&&y<n;
+}
+
+int wyspy(vector<vector<bool>> &adj){
+	int n=adj.size(), m=adj[0].size(), ans=0;
+	vector<vector<bool>> vis(n, vector<bool>(m, 0));
+	deque<array<int, 3>> dq;
+	for (int i=0; i<m; ++i){
+		vis[0][i]=vis[n-1][i]=1;
+		if(adj[0][i])
+			dq.push_back({1, 0, i});
+		else 
+			dq.push_front({0, 0, i});
+		if(adj[n-1][i])
+			dq.push_back({1, n-1, i});
+		else
+			dq.push_front({0, n-1, i});
+	}
+	for (int i=0; i<n; ++i){
+		vis[i][0]=vis[i][m-1]=1;
+		if(adj[i][0])
+			dq.push_back({1, i, 0});
+		else 
+			dq.push_front({0, i, 0});
+		if(adj[i][m-1])
+			dq.push_back({1, i, m-1});
+		else
+			dq.push_front({0, i, m-1});
+	}
+	while(!dq.empty()){
+		array<int, 3> u=dq.front(); dq.pop_front();
+		ans=max(ans, u[0]);
+		for (int i=0; i<4; ++i){
+			int y=u[1]+dy[i], x=u[2]+dx[i];
+			if(!ok(y, x, n, m)||vis[y][x]) continue;
+			vis[y][x]=1;
+			if(adj[y][x]==adj[u[1]][u[2]]) dq.push_front({u[0], y, x});
+			else dq.push_back({u[0]+1, y, x});
+		}
+	}
+	return ans;
+}
+
+int main(){
+	ios::sync_with_stdio(0);
+	cin.tie(0);
+
+	int n, m;
+	cin >> n >> m;
+	vector<vector<bool>> adj(n, vector<bool>(m, 0));
+	for (int i=0; i<n; ++i){
+		for (int j=0; j<m; ++j){
+			int x;
+			cin >> x;
+			if(x) adj[i][j]=1;
+		}
+	}
+	cout << wyspy(adj);
+}