Permutation in String
Given two strings s1 and s2, write a function to return true if s2 contains the permutation of s1. In other words, one of the first string's permutations is the substring of the second string.
Example 1:
Input: s1 = "ab" s2 = "eidbaooo"
Output: True
Explanation: s2 contains one permutation of s1 ("ba").
Example 2:
Input:s1= "ab" s2 = "eidboaoo"
Output: False
Constraints:
The input strings only contain lower case letters.
The length of both given strings is in range [1, 10,000].
class Solution {
public boolean checkInclusion(String s1, String s2) {
int count = s1.length();
int[] freq = new int[26];
boolean[] isPresent = new boolean[26];
for (char x : s1.toCharArray()) {
isPresent[x - 'a'] = true;
freq[x - 'a']++;
}
int start = 0, end = 0;
while (end < s2.length()) {
char c = s2.charAt(end);
if (freq[c - 'a'] > 0) {
freq[c - 'a']--;
count--;
if (count == 0)
return true;
} else {
while (start <= end) {
if (s2.charAt(start) == c) {
start++;
break;
}
freq[s2.charAt(start) - 'a']++;
start++;
count++;
}
}
end++;
}
return false;
}
}
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