Time: 45 ms (13.98%), Space: 14.4 MB (97.88%) - LeetHub

Author: JanaSabuj

shortest-path-with-alternating-colors/shortest-path-with-alternating-colors.cpp

@@ -0,0 +1,56 @@
+# define RED 0
+# define BLUE 1
+class Solution {
+    int dist[2][105];
+public:
+    Solution(){
+        memset(dist, -1, sizeof(dist));
+    }    
+
+    void bfs(int src, vector<pair<int, int>> adj[]) {
+        queue<pair<int,int>> q;
+        q.push({src, RED});
+        q.push({src, BLUE});
+        dist[RED][src] = 0;
+        dist[BLUE][src] = 0;
+
+        while(!q.empty()){
+            auto curr = q.front(); q.pop();
+            int v = curr.first;
+            int color_prev = curr.second;
+
+            for(auto u: adj[v]){
+                if(u.second == !color_prev){                    
+                    int to = u.first;
+                    int to_color = u.second;
+                    if(dist[to_color][to] == -1){
+                        dist[to_color][to] = dist[color_prev][v] + 1;
+                        q.push({to, to_color});
+                    }
+                }
+            }
+        }
+    }
+
+    vector<int> shortestAlternatingPaths(int n, vector<vector<int>>& red_edges, vector<vector<int>>& blue_edges) {
+        vector<pair<int, int>> adj[n];   
+        for(auto& r: red_edges){
+            adj[r[0]].push_back({r[1], RED});
+        }
+
+        for(auto& b: blue_edges){
+            adj[b[0]].push_back({b[1], BLUE});
+        }
+
+        bfs(0, adj);
+        vector<int> ans(n);
+        for (int i = 0; i < n; ++i){
+            cout << dist[RED][i] << " " << dist[BLUE][i] << endl;
+            ans[i] = min(dist[RED][i] == -1 ? INT_MAX : dist[RED][i], dist[BLUE][i] == -1 ? INT_MAX : dist[BLUE][i]);
+            if(ans[i] == INT_MAX)
+                ans[i] = -1;
+        }
+
+        return ans;
+    }
+};