graph

1627. Graph Connectivity With Threshold.cpp

@@ -1,3 +1,4 @@
+//graph
 //WA
 //57 / 66 test cases passed.
 //indirectly connection also considered true?
@@ -41,6 +42,75 @@ class Solution {
     }
 };
 
+//graph
+//fix above: indirectly connected cities should also be seen as connected
+//TLE
+//64 / 66 test cases passed.
+class Solution {
+public:
+    int gcd(int x, int y){
+        if(y == 0) return x;
+        return gcd(y, x%y);
+    }
+
+    int encode(int& i, int& j, int& n){
+        return i*(n+1)+j;
+    }
+
+    vector<bool> areConnected(int n, int threshold, vector<vector<int>>& queries) {
+        int m = queries.size();
+        vector<bool> ans(m, true);
+
+        if(threshold == 0){
+            return ans;
+        }
+
+        vector<unordered_set<int>> adjList(n+1);
+
+        for(int i = 1; i <= n; ++i){
+            for(int j = i+1; j <= n; ++j){
+                if(gcd(i, j) > threshold){
+                    adjList[i].insert(j);
+                    adjList[j].insert(i);
+                }
+            }
+        }
+
+        for(int i = 0; i < m; ++i){
+            vector<int>& query = queries[i];
+            if(query[0] > query[1]) swap(query[0], query[1]);
+
+            bool connected = false;
+
+            queue<int> q;
+            vector<bool> visited(n+1, false);
+            int cur;
+
+            q.push(query[0]);
+            visited[query[0]] = true;
+
+            while(!q.empty()){
+                cur = q.front(); q.pop();
+
+                if(cur == query[1]){
+                    connected = true;
+                    break;
+                }
+
+                for(const int& nei : adjList[cur]){
+                    if(visited[nei]) continue;
+                    visited[nei] = true;
+                    q.push(nei);
+                }
+            }
+
+            ans[i] = connected;
+        }
+
+        return ans;
+    }
+};
+
 //DSU
 //from hint
 //Runtime: 360 ms, faster than 57.32% of C++ online submissions for Graph Connectivity With Threshold.