100% Java Solution✔✔✔⚡⚡⚡
IntuitionApproachComplexity
Time complexity:

Space complexity:
Code
# Intuition
<!-- Describe your first thoughts on how to solve this problem. -->

# Approach
<!-- Describe your approach to solving the problem. -->

# Complexity
- Time complexity:
<!-- Add your time complexity here, e.g. $$O(n)$$ -->

- Space complexity:
<!-- Add your space complexity here, e.g. $$O(n)$$ -->

# Code
```java []
class Solution {
    public int numberOfSubstrings(String s, int k) {
        HashMap<Character,Integer>map=new HashMap<>();
         int n=s.length();
         int ans=0;
         int left=0;
        for(int i=0; i<n; i++){
            char c=s.charAt(i);
            map.put(c,map.getOrDefault(c,0)+1);
            if(map.get(c)==k){
                while(map.get(c)==k){
                    ans+=n-i;
                    char ch=s.charAt(left);
                    map.put(ch,map.get(ch)-1);
                    left++;
                }
            }
        }
     return ans;
    }
}
```
['Java']