def largestPathValue(self, colors, edges):

n, k = len(colors), 26

indegrees = [0] * n

graph = [[] for _ in range(n)]

for u, v in edges:

graph[u].append(v)

indegrees[v] += 1

zero_indegree = set(i for i in range(n) if indegrees[i] == 0)

counts = [[0] * k for _ in range(n)]

for i, c in enumerate(colors):

counts[i][ord(c) - ord('a')] += 1

max_count, visited = 0, 0

while zero_indegree:

u = zero_indegree.pop()

visited += 1

for v in graph[u]:

for i in range(k):

counts[v][i] = max(counts[v][i], counts[u][i] + (ord(colors[v]) - ord('a') == i))

indegrees[v] -= 1

if indegrees[v] == 0:

zero_indegree.add(v)

max_count = max(max_count, max(counts[u]))