4052. Equal Score Substrings

Easy

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You are given a string s consisting of lowercase English letters.

The score of a string is the sum of the positions of its characters in the alphabet, where 'a' = 1, 'b' = 2, ..., 'z' = 26.

Determine whether there exists an index i such that the string can be split into two non-empty substrings s[0..i] and s[(i + 1)..(n - 1)] that have equal scores.

Return true if such a split exists, otherwise return false.

 

Example 1:

Input: s = "adcb"

Output: true

Explanation:

Split at index i = 1:

• Left substring = s[0..1] = "ad" with score = 1 + 4 = 5
• Right substring = s[2..3] = "cb" with score = 3 + 2 = 5

Both substrings have equal scores, so the output is true.

Example 2:

Input: s = "bace"

Output: false

Explanation:​​​​​​

​​​​​​​No split produces equal scores, so the output is false.

 

Constraints:

• 2 <= s.length <= 100
• s consists of lowercase English letters.

// Add your C++ solution here

class Solution {
    public boolean scoreBalance(String s) {
        int n = s.length();
        int pref[] = new int[n];
        int suff[] = new int[n];
        pref[0] = s.charAt(0) - 'a' + 1;
        suff[n - 1] = s.charAt(n - 1) - 'a' + 1;
        for (int i = 1; i < n; i++)
            pref[i] = pref[i - 1] + s.charAt(i) - 'a' + 1;
        for (int i = n - 2; i >= 0; i--)
            suff[i] = suff[i + 1] + s.charAt(i) - 'a' + 1;
        for (int i = 0; i < n - 1; i++) {
            if (pref[i] == suff[i + 1])
                return true;
        }
        return false;
    }
}