Create maximal-network-rank.cpp

Author: kamyu104

C++/maximal-network-rank.cpp

@@ -0,0 +1,60 @@
+// Time:  O(nlogn) ~ O(n^2)
+// Space: O(m + n)
+
+class Solution {
+public:
+    int maximalNetworkRank(int n, vector<vector<int>>& roads) {
+        vector<int> degree(n);
+        unordered_map<int, unordered_set<int>> adj;
+        for (const auto& road : roads) {
+            ++degree[road[0]];
+            ++degree[road[1]];
+            adj[road[0]].emplace(road[1]);
+            adj[road[1]].emplace(road[0]);
+        }
+        vector<int> sorted_idx(n);
+        iota(begin(sorted_idx), end(sorted_idx), 0);
+        sort(begin(sorted_idx), end(sorted_idx),
+             [&degree](const auto& a, const auto& b) {
+                 return degree[a] > degree[b];
+             });
+        int m = 2;
+        for (; m < n; ++m) {
+            if (degree[sorted_idx[m]] != degree[sorted_idx[1]]) {
+                break;
+            }
+        }
+        int result = degree[sorted_idx[0]] + degree[sorted_idx[1]] - 1;
+        for (int i = 0; i < m - 1; ++i) {
+            for (int j = i + 1; j < m; ++j) {
+                if (degree[sorted_idx[i]] + degree[sorted_idx[j]] - int(adj.count(sorted_idx[i]) && adj[sorted_idx[i]].count(sorted_idx[j])) > result) {
+                    return degree[sorted_idx[i]] + degree[sorted_idx[j]] - int(adj.count(sorted_idx[i]) && adj[sorted_idx[i]].count(sorted_idx[j]));
+                }
+            }
+        }
+        return result;
+    }
+};
+
+// Time:  O(n^2)
+// Space: O(m + n)
+class Solution2 {
+public:
+    int maximalNetworkRank(int n, vector<vector<int>>& roads) {
+        vector<int> degree(n);
+        unordered_map<int, unordered_set<int>> adj;
+        for (const auto& road : roads) {
+            ++degree[road[0]];
+            ++degree[road[1]];
+            adj[road[0]].emplace(road[1]);
+            adj[road[1]].emplace(road[0]);
+        }
+        int result = 0;
+        for (int i = 0; i < n - 1; ++i) {
+            for (int j = i + 1; j < n; ++j) {
+                result = max(result, degree[i] + degree[j] - int(adj.count(i) && adj[i].count(j)));
+            }
+        }
+        return result;
+    }
+};