LC-0664 Hard LeetCode

664. Strange Printer

Read the full problem statement on LeetCode.

Difficulty: hard Acceptance: 61% Topics: String, Dynamic Programming

Reading material

Strings 12 min 1-D Dynamic Programming 16 min

Reference solution (spoiler · python)

# Time:  O(n^3)
# Space: O(n^2)

class Solution(object):
    def strangePrinter(self, s):
        """
        :type s: str
        :rtype: int
        """
        def dp(s, i, j, lookup):
            if i > j:
                return 0
            if (i, j) not in lookup:
                lookup[(i, j)]  = dp(s, i, j-1, lookup) + 1
                for k in xrange(i, j):
                    if s[k] == s[j]:
                        lookup[(i, j)] = min(lookup[(i, j)], \
                                             dp(s, i, k, lookup) + dp(s, k+1, j-1, lookup))
            return lookup[(i, j)]

        lookup = {}
        return dp(s, 0, len(s)-1, lookup)

Solution from kamyu104/LeetCode-Solutions · MIT