# Longest Substring with At Least K Repeating Characters LeetCode Solution

Here, We see Longest Substring with At Least K Repeating Characters LeetCode Solution. This Leetcode problem is done in many programming languages like C++, Java, JavaScript, Python, etc. with different approaches.

# List of all LeetCode Solution

## Problem Statement

Given a string `s` and an integer `k`, return the length of the longest substring of `s` such that the frequency of each character in this substring is greater than or equal to `k`.

if no such substring exists, return 0.

Example 1:
Input: s = “aaabb”, k = 3
Output: 3
Explanation: The longest substring is “aaa”, as ‘a’ is repeated 3 times.

Example 2:
Input: s = “ababbc”, k = 2
Output: 5
Explanation: The longest substring is “ababb”, as ‘a’ is repeated 2 times and ‘b’ is repeated 3 times.

## Longest Substring with At Least K Repeating Characters LeetCode Solution C++

``````class Solution {
public:
int longestSubstring(string s, int k) {
int n = s.length();
if(n == 0 or n < k) return 0;
if(k <= 1) return n;
unordered_map<char,int> countMap;
for(char c : s) countMap[c]++;
int left =0;
while(left < n && countMap[s[left]] >= k) left++;
if(left >= n-1) return left;
int l1 = longestSubstring(s.substr(0,left) ,k);
while(left < n && countMap[s[left]] < k) left++;
int l2 = left < n ? longestSubstring(s.substr(left),k) : 0;
return max(l1,l2);
}
};```Code language: PHP (php)```

## Longest Substring with At Least K Repeating Characters LeetCode Solution Java

``````class Solution {
public int longestSubstring(String s, int k) {
if (s == null || s.length() == 0) return 0;
char[] chars = new char[26];
for (int i = 0; i < s.length(); i += 1) chars[s.charAt(i) - 'a'] += 1;
boolean flag = true;
for (int i = 0; i < chars.length; i += 1) {
if (chars[i] < k && chars[i] > 0) flag = false;
}
if (flag == true) return s.length();
int result = 0;
int start = 0, cur = 0;
while (cur < s.length()) {
if (chars[s.charAt(cur) - 'a'] < k) {
result = Math.max(result, longestSubstring(s.substring(start, cur), k));
start = cur + 1;
}
cur++;
}
result = Math.max(result, longestSubstring(s.substring(start), k));
return result;
}
}```Code language: JavaScript (javascript)```

## Longest Substring with At Least K Repeating Characters LeetCode Solution JavaScript

``````var longestSubstring = function(s, k) {
let maxUnique = new Set(s).size;
let max = 0;
for (let curUnique = 1; curUnique <= maxUnique; curUnique++) {
let start = 0, end = 0, atLeastK = 0, unique = 0, m = new Map();
while (end < s.length) {
m.set(s[end], m.get(s[end]) + 1 || 1);
if (m.get(s[end]) == 1) unique++;
if (m.get(s[end]) == k) atLeastK++;
while (unique > curUnique) {
m.set(s[start], m.get(s[start]) - 1);
if (m.get(s[start]) == k-1) atLeastK--;
if (m.get(s[start]) == 0) unique--;
start++;
}
if (unique == curUnique && unique == atLeastK) {
max = Math.max(max, end - start + 1);
}
end++;
}
}
return max;
};```Code language: JavaScript (javascript)```

## Longest Substring with At Least K Repeating Characters LeetCode Solution Python

``````class Solution(object):
def longestSubstring(self, s, k):
cnt = collections.Counter(s)
st = 0
maxst = 0
for i, c in enumerate(s):
if cnt[c] < k:
maxst = max(maxst, self.longestSubstring(s[st:i], k))
st = i + 1
return len(s) if st == 0 else max(maxst, self.longestSubstring(s[st:], k))```Code language: HTML, XML (xml)```
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