Largest Color Value in a Directed Graph.java

class Solution {
    public int largestPathValue(String colors, int[][] edges) {
        int n = colors.length();
        Map<Integer, List<Integer>> graph = new HashMap<>();
        int[] indegree = new int[n];
        for (int[] edge : edges) {
            graph.computeIfAbsent(edge[0], k -> new ArrayList<>())
                .add(edge[1]);
            indegree[edge[1]]++;
        }
        int[][] count = new int[n][26];
        Queue<Integer> queue = new LinkedList<>();
        for (int i = 0; i < n; i++) {
            if (indegree[i] == 0) {
                queue.add(i);
            }
        }
        int result = 1;
        int seen = 0;
        while (!queue.isEmpty()) {
            int node = queue.remove();
            result = Math.max(result, ++count[node][colors.charAt(node) - 'a']);
            seen++;
            if (!graph.containsKey(node)) {
                continue;
            }
            for (int neighbor : graph.get(node)) {
                for (int i = 0; i < 26; i++) {
                    count[neighbor][i] = Math.max(count[neighbor][i], count[node][i]);
                }
                indegree[neighbor]--;
                if (indegree[neighbor] == 0) {
                    queue.add(neighbor);
                }
            }
        }
        return seen < n ? -1 : result;
    }
}