Repeating String - Amazon Top Interview Questions
Problem Statement :
Given a lowercase alphabet string s, return whether it's a repeating string. Constraints n ≤ 100,000 where n is the length of s Example 1 Input s = "dogdogdog" Output True Explanation "dog" is repeated. Example 2 Input s = "catdog" Output False
Solution :
Solution in C++ :
bool solve(string s) {
const size_t size_2 = s.size() >> 1;
for (size_t pattern_size = s.find(s[0], 1); pattern_size <= size_2;
pattern_size = s.find(s[0], pattern_size + 1)) {
const size_t N = s.size() / pattern_size;
if (N * pattern_size == s.size()) {
if (N & 1) {
const size_t ssize = s.size() - pattern_size;
const size_t half = ssize >> 1;
if (memcmp(&s[0], &s[ssize], pattern_size) == 0 &&
memcmp(&s[0], &s[half], half) == 0)
return true;
} else {
if (memcmp(&s[0], &s[size_2], size_2) == 0) return true;
}
}
}
return false;
}
Solution in Java :
import java.util.*;
class Solution {
public boolean solve(String s) {
return ((s + s).indexOf(s, 1) != s.length());
}
}
Solution in Python :
class Solution:
def solve(self, s):
if len(s) == 1:
return False
for i in range(1, len(s) // 2 + 1):
if len(s) % i == 0:
reciprocal = len(s) // i
if s == s[:i] * reciprocal:
return True
return False
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