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| 1 | +class Solution { |
| 2 | +public: |
| 3 | + int maxi = -1; |
| 4 | + int dp[100001][26]; |
| 5 | + bool dfs(int node, vector<int> adj[], vector<int>& vis, string& colors) { |
| 6 | + vis[node] = 1; |
| 7 | + dp[node][colors[node] - 'a']++; |
| 8 | + for (auto it : adj[node]) { |
| 9 | + if (!vis[it]) { |
| 10 | + if (dfs(it, adj, vis, colors)) |
| 11 | + return true; |
| 12 | + } |
| 13 | + |
| 14 | + for (int i = 0; i < 26; i++) |
| 15 | + if (colors[node] - 'a' == i) |
| 16 | + dp[node][i] = max(dp[node][i], dp[it][i] + 1); |
| 17 | + else |
| 18 | + dp[node][i] = max(dp[node][i], dp[it][i]); |
| 19 | + } |
| 20 | + for(int i=0;i<26;i++)maxi=max(maxi,dp[node][i]); |
| 21 | + return false; |
| 22 | + } |
| 23 | + int largestPathValue(string colors, vector<vector<int>>& edges) { |
| 24 | + int n = colors.size(); |
| 25 | + memset(dp, 0, sizeof(dp)); |
| 26 | + vector<int> adj[n]; |
| 27 | + queue<int> q, p; |
| 28 | + vector<int> indegree(n, 0); |
| 29 | + // creating adjacency matrix |
| 30 | + for (auto it : edges) { |
| 31 | + adj[it[0]].push_back(it[1]); |
| 32 | + indegree[it[1]]++; |
| 33 | + } |
| 34 | + // topological sort using kahn's algo |
| 35 | + for (int i = 0; i < n; i++) |
| 36 | + if (indegree[i] == 0) { |
| 37 | + q.push(i); |
| 38 | + p.push(i); |
| 39 | + } |
| 40 | + vector<int> z; |
| 41 | + while (!p.empty()) { |
| 42 | + int node = p.front(); |
| 43 | + p.pop(); |
| 44 | + z.push_back(node); |
| 45 | + for (auto it : adj[node]) { |
| 46 | + indegree[it]--; |
| 47 | + if (indegree[it] == 0) |
| 48 | + p.push(it); |
| 49 | + } |
| 50 | + } |
| 51 | + //if cycle is present return -1 |
| 52 | + if (z.size() != n) |
| 53 | + return -1; |
| 54 | + vector<int> vis(n, false), pathvis(n, false); |
| 55 | + // making dfs calls only for nodes which have zero indegree |
| 56 | + // other nodes will be included automatically in |
| 57 | + // the dp table by dfc calls of these nodes |
| 58 | + while (!q.empty()) { |
| 59 | + int node = q.front(); |
| 60 | + q.pop(); |
| 61 | + if (dfs(node, adj, vis, colors)) |
| 62 | + return -1; |
| 63 | + } |
| 64 | + return maxi; |
| 65 | + } |
| 66 | +}; |
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