Substring With Largest Variance

// Accepted solution for LeetCode #2272: Substring With Largest Variance
class Solution {
    public int largestVariance(String s) {
        int n = s.length();
        int ans = 0;
        for (char a = 'a'; a <= 'z'; ++a) {
            for (char b = 'a'; b <= 'z'; ++b) {
                if (a == b) {
                    continue;
                }
                int[] f = new int[] {0, -n};
                for (int i = 0; i < n; ++i) {
                    if (s.charAt(i) == a) {
                        f[0]++;
                        f[1]++;
                    } else if (s.charAt(i) == b) {
                        f[1] = Math.max(f[0] - 1, f[1] - 1);
                        f[0] = 0;
                    }
                    ans = Math.max(ans, f[1]);
                }
            }
        }
        return ans;
    }
}

// Accepted solution for LeetCode #2272: Substring With Largest Variance
func largestVariance(s string) int {
	ans, n := 0, len(s)
	for a := 'a'; a <= 'z'; a++ {
		for b := 'a'; b <= 'z'; b++ {
			if a == b {
				continue
			}
			f := [2]int{0, -n}
			for _, c := range s {
				if c == a {
					f[0]++
					f[1]++
				} else if c == b {
					f[1] = max(f[1]-1, f[0]-1)
					f[0] = 0
				}
				ans = max(ans, f[1])
			}
		}
	}
	return ans
}

# Accepted solution for LeetCode #2272: Substring With Largest Variance
class Solution:
    def largestVariance(self, s: str) -> int:
        ans = 0
        for a, b in permutations(ascii_lowercase, 2):
            if a == b:
                continue
            f = [0, -inf]
            for c in s:
                if c == a:
                    f[0], f[1] = f[0] + 1, f[1] + 1
                elif c == b:
                    f[1] = max(f[1] - 1, f[0] - 1)
                    f[0] = 0
                if ans < f[1]:
                    ans = f[1]
        return ans

// Accepted solution for LeetCode #2272: Substring With Largest Variance
/**
 * [2272] Substring With Largest Variance
 *
 * The variance of a string is defined as the largest difference between the number of occurrences of any 2 characters present in the string. Note the two characters may or may not be the same.
 * Given a string s consisting of lowercase English letters only, return the largest variance possible among all substrings of s.
 * A substring is a contiguous sequence of characters within a string.
 *  
 * Example 1:
 *
 * Input: s = "aababbb"
 * Output: 3
 * Explanation:
 * All possible variances along with their respective substrings are listed below:
 * - Variance 0 for substrings "a", "aa", "ab", "abab", "aababb", "ba", "b", "bb", and "bbb".
 * - Variance 1 for substrings "aab", "aba", "abb", "aabab", "ababb", "aababbb", and "bab".
 * - Variance 2 for substrings "aaba", "ababbb", "abbb", and "babb".
 * - Variance 3 for substring "babbb".
 * Since the largest possible variance is 3, we return it.
 *
 * Example 2:
 *
 * Input: s = "abcde"
 * Output: 0
 * Explanation:
 * No letter occurs more than once in s, so the variance of every substring is 0.
 *
 *  
 * Constraints:
 *
 * 	1 <= s.length <= 10^4
 * 	s consists of lowercase English letters.
 *
 */
pub struct Solution {}

// problem: https://leetcode.com/problems/substring-with-largest-variance/
// discuss: https://leetcode.com/problems/substring-with-largest-variance/discuss/?currentPage=1&orderBy=most_votes&query=

// submission codes start here

impl Solution {
    pub fn largest_variance(s: String) -> i32 {
        0
    }
}

// submission codes end

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    #[ignore]
    fn test_2272_example_1() {
        let s = "aababbb".to_string();

        let result = 3;

        assert_eq!(Solution::largest_variance(s), result);
    }

    #[test]
    #[ignore]
    fn test_2272_example_2() {
        let s = "abcde".to_string();

        let result = 0;

        assert_eq!(Solution::largest_variance(s), result);
    }
}

// Accepted solution for LeetCode #2272: Substring With Largest Variance
function largestVariance(s: string): number {
    const n: number = s.length;
    let ans: number = 0;
    for (let a = 97; a <= 122; ++a) {
        for (let b = 97; b <= 122; ++b) {
            if (a === b) {
                continue;
            }
            const f: number[] = [0, -n];
            for (let i = 0; i < n; ++i) {
                if (s.charCodeAt(i) === a) {
                    f[0]++;
                    f[1]++;
                } else if (s.charCodeAt(i) === b) {
                    f[1] = Math.max(f[0] - 1, f[1] - 1);
                    f[0] = 0;
                }
                ans = Math.max(ans, f[1]);
            }
        }
    }
    return ans;
}