LC-2223 Hard LeetCode

2223. Sum of Scores of Built Strings

String Binary Search Rolling Hash Suffix Array String Matching Hash Function

Read the full problem statement on LeetCode.

Difficulty: hard Acceptance: 42% Topics: String, Binary Search, Rolling Hash, Suffix Array, String Matching, Hash Function

View full problem on LeetCode

Reading material

Strings 12 min Binary Search 12 min String Matching & Hashing 13 min

Reference solution (spoiler · python)

# Time:  O(n)
# Space: O(n)

# z-function
class Solution(object):
    def sumScores(self, s):
        """
        :type s: str
        :rtype: int
        """
        # Template: https://cp-algorithms.com/string/z-function.html
        def z_function(s):  # Time: O(n), Space: O(n)
            z = [0]*len(s)
            l, r = 0, 0
            for i in xrange(1, len(z)):
                if i <= r:
                    z[i] = min(r-i+1, z[i-l])
                while i+z[i] < len(z) and s[z[i]] == s[i+z[i]]:
                    z[i] += 1
                if i+z[i]-1 > r:
                    l, r = i, i+z[i]-1
            return z

        z = z_function(s)
        z[0] = len(s)
        return sum(z)

Solution from kamyu104/LeetCode-Solutions · MIT