func minimumTime(n int, relations [][]int, time []int) int { graph := map[int][][2]int{} for _, rel := range relations { graph[rel[0]] = append(graph[rel[0]], [2]int{rel[1], time[rel[1]-1]}) } memo := make([]int, n+1) var fn func(node int) int fn = func(node int) int { if memo[node] != 0 { return memo[node] } maxi := 0 for _, ngb := range graph[node] { if memo[ngb[0]] != 0 { maxi = max(memo[ngb[0]], maxi ) } maxi = max(fn(ngb[0]), maxi) } memo[node] = time[node-1]+maxi return memo[node] } result := 0 for i := 1; i <= n; i++ { result = max(result, fn(i)) } return result } https://leetcode.com/problems/parallel-courses-iii/ topics: #graph #memoization #dfs level: #hard