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MEDIUM 30 Jun 2026

1358. Number of Substrings Containing All Three Characters

</> Solution

class Solution {
    public int numberOfSubstrings(String s) {
        int[] count = new int[3];
        int left = 0;
        int ans = 0;

        for (int right = 0; right < s.length(); right++) {
            count[s.charAt(right) - 'a']++;

            while (count[0] > 0 && count[1] > 0 && count[2] > 0) {
                ans += s.length() - right;
                count[s.charAt(left) - 'a']--;
                left++;
            }
        }

        return ans;
    }
}

TIME COMPLEXITY

O(n)

SPACE COMPLEXITY

O(1)