1553. Minimum Number of Days to Eat N Oranges - Explanation

class Solution:
    def minDays(self, n: int) -> int:
        dp = {}

        def dfs(n):
            if n == 0:
                return 0
            if n in dp:
                return dp[n]

            res = 1 + dfs(n - 1)
            if n % 3 == 0:
                res = min(res, 1 + dfs(n // 3))
            if n % 2 == 0:
                res = min(res, 1 + dfs(n // 2))

            dp[n] = res
            return res

        return dfs(n)

class Solution:
    def minDays(self, n: int) -> int:
        dp = {0: 0, 1: 1}

        def dfs(n):
            if n in dp:
                return dp[n]

            res = 1 + (n % 2) + dfs(n // 2)
            res = min(res, 1 + (n % 3) + dfs(n // 3))
            dp[n] = res
            return res

        return dfs(n)

class Solution:
    def minDays(self, n: int) -> int:
        q = deque([n])
        visit = set()
        res = 0

        while q:
            res += 1
            for _ in range(len(q)):
                node = q.popleft()
                nei = node - 1
                if nei == 0:
                    return res
                if nei not in visit:
                    visit.add(nei)
                    q.append(nei)
                for d in range(2, 4):
                    if node % d == 0:
                        nei = node // d
                        if nei == 0:
                            return res
                        if nei not in visit:
                            visit.add(nei)
                            q.append(nei)
        return res