Class Solution
- java.lang.Object
-
- g2101_2200.s2156_find_substring_with_given_hash_value.Solution
-
public class Solution extends Object
2156 - Find Substring With Given Hash Value.Hard
The hash of a 0-indexed string
s
of lengthk
, given integersp
andm
, is computed using the following function:hash(s, p, m) = (val(s[0]) * p0 + val(s[1]) * p1 + … + val(s[k-1]) * pk-1) mod m
.
Where
val(s[i])
represents the index ofs[i]
in the alphabet fromval('a') = 1
toval('z') = 26
.You are given a string
s
and the integerspower
,modulo
,k
, andhashValue.
Returnsub
, the first substring ofs
of lengthk
such thathash(sub, power, modulo) == hashValue
.The test cases will be generated such that an answer always exists.
A substring is a contiguous non-empty sequence of characters within a string.
Example 1:
Input: s = “leetcode”, power = 7, modulo = 20, k = 2, hashValue = 0
Output: “ee”
Explanation: The hash of “ee” can be computed to be hash(“ee”, 7, 20) = (5 * 1 + 5 * 7) mod 20 = 40 mod 20 = 0. “ee” is the first substring of length 2 with hashValue 0. Hence, we return “ee”.
Example 2:
Input: s = “fbxzaad”, power = 31, modulo = 100, k = 3, hashValue = 32
Output: “fbx”
Explanation: The hash of “fbx” can be computed to be hash(“fbx”, 31, 100) = (6 * 1 + 2 * 31 + 24 * 312) mod 100 = 23132 mod 100 = 32.
The hash of “bxz” can be computed to be hash(“bxz”, 31, 100) = (2 * 1 + 24 * 31 + 26 * 312) mod 100 = 25732 mod 100 = 32. “fbx” is the first substring of length 3 with hashValue 32. Hence, we return “fbx”.
Note that “bxz” also has a hash of 32 but it appears later than “fbx”.
Constraints:
1 <= k <= s.length <= 2 * 104
1 <= power, modulo <= 109
0 <= hashValue < modulo
s
consists of lowercase English letters only.- The test cases are generated such that an answer always exists.
-
-
Constructor Summary
Constructors Constructor Description Solution()
-
Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description String
subStrHash(String s, int power, int modulo, int k, int hashValue)
-