Create 2378.Choose-Edges-to-Maximize-Score-in-a-Tree.cpp

Dynamic_Programming/2378.Choose-Edges-to-Maximize-Score-in-a-Tree/2378.Choose-Edges-to-Maximize-Score-in-a-Tree.cpp

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+using LL = long long;
+class Solution {
+    vector<pair<int,LL>>children[100005];
+    LL memo[100005][2];
+public:
+    long long maxScore(vector<vector<int>>& edges) 
+    {
+        int n = edges.size();
+        int root = -1;
+        for (int i=0; i<n; i++)
+        {
+            if (edges[i][0]==-1) 
+            {
+                root = i;
+                continue;
+            }
+            int par = edges[i][0];
+            int weight = edges[i][1];
+            children[par].push_back({i, weight});
+        }
+
+        return dfs(root, 0);        
+    }
+
+    LL dfs(int node, int status)
+    {
+        if (memo[node][status]!=0)
+            return memo[node][status];
+
+        if (status == 0)
+        {
+            LL sum = 0;
+            for (auto& [child, weight]: children[node])
+                sum += dfs(child, 0);
+
+            LL maxSum = sum;
+            for (auto& [child, weight]: children[node])
+                maxSum = max(maxSum, sum - dfs(child, 0) + dfs(child, 1) + weight);                
+
+            memo[node][0] = maxSum;
+            return maxSum;
+        }
+        else
+        {
+            LL sum = 0;
+            for (auto& [child, weight]: children[node])
+                sum += dfs(child, 0);
+            memo[node][1] = sum;
+            return sum;
+        }
+    }
+};