Merge branch 'main' into temp

Author: SjxSubham

1857. Largest_Color_Value_in_a_Directed_Graph.cpp

@@ -0,0 +1,64 @@
+// Use Topological Sorting (Kahn’s Algorithm) + Dynamic Programming.
+
+// For each node, maintain a count[node][color] array of size 26.
+
+// When processing a node, propagate color counts to its neighbors.
+
+// Keep track of max color count during traversal.
+
+// If all nodes are processed → return max count; else → cycle → -1.
+
+
+#include <iostream>
+#include <vector>
+#include <queue>
+#include <unordered_map>
+#include <string>
+#include <algorithm>
+#include <climits>
+using namespace std;
+
+class Solution {
+public:
+    int largestPathValue(string colors, vector<vector<int>>& edges) {
+        int n=colors.size();
+        vector<vector<int>> graph(n);
+        vector<int> indegree(n, 0);
+
+        
+        for (auto &e:edges) {
+            graph[e[0]].push_back(e[1]);
+            indegree[e[1]]++;
+        }
+
+        
+        queue<int> q;
+        for (int i=0;i<n;i++)
+            if (indegree[i]==0)
+                q.push(i);
+
+        vector<vector<int>> count(n,vector<int>(26, 0)); 
+        int vis=0;
+        int ans=0;
+
+        while (!q.empty()) {
+            int u=q.front();
+            q.pop();
+            vis++;
+
+
+            int colorIdx=colors[u]-'a';
+            count[u][colorIdx]++;
+            ans=max(ans,count[u][colorIdx]);
+
+            for(int v:graph[u]) {
+                for(int c=0;c<26;c++)
+                    count[v][c] = max(count[v][c],count[u][c]);
+                if(--indegree[v]==0)
+                    q.push(v);
+            }
+        }
+
+        return (vis==n)?ans:-1;
+    }
+};