Solution.go

func largestPathValue(colors string, edges [][]int) int {
	n := len(colors)
	g := make([][]int, n)
	indeg := make([]int, n)
	for _, e := range edges {
		a, b := e[0], e[1]
		g[a] = append(g[a], b)
		indeg[b]++
	}
	q := []int{}
	dp := make([][]int, n)
	for i := range dp {
		dp[i] = make([]int, 26)
	}
	for i, v := range indeg {
		if v == 0 {
			q = append(q, i)
			c := colors[i] - 'a'
			dp[i][c]++
		}
	}
	cnt := 0
	ans := 1
	for len(q) > 0 {
		i := q[0]
		q = q[1:]
		cnt++
		for _, j := range g[i] {
			indeg[j]--
			if indeg[j] == 0 {
				q = append(q, j)
			}
			c := int(colors[j] - 'a')
			for k := 0; k < 26; k++ {
				t := 0
				if c == k {
					t = 1
				}
				dp[j][k] = max(dp[j][k], dp[i][k]+t)
				ans = max(ans, dp[j][k])
			}
		}
	}
	if cnt == n {
		return ans
	}
	return -1
}

func max(a, b int) int {
	if a > b {
		return a
	}
	return b
}