# 05.02.2025 [1790. Check if One String Swap Can Make Strings Equal]

One swap to make stings equal #easy

05.02.2025

1790. Check if One String Swap Can Make Strings Equal easy blog post substack youtube

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Problem TLDR

One swap to make stings equal #easy

Intuition

Find all the differences, then analyze them. Or do a single swap, then compare strings.

Approach

• zip - unzip is a good match here

Complexity

• Time complexity: $$O(n)$$

• Space complexity: $$O(1)$$ or O(n) for Kotlin/Rust worst

Code

    fun areAlmostEqual(s1: String, s2: String) = 
        s1.zip(s2).filter { (a, b) -> a != b }.unzip()
        .let { (a, b) -> a.size < 3 && a == b.reversed() }

    pub fn are_almost_equal(s1: String, s2: String) -> bool {
        let (a, mut b): (Vec<_>, Vec<_>) = s1.bytes().zip(s2.bytes())
        .filter(|(a, b)| a != b).unzip(); b.reverse(); a.len() < 3 && a == b
    }

    bool areAlmostEqual(string s1, string s2) {
        for (int i = 0, j = -1, c = 0; i < size(s1) && !c; ++i)
            if (s1[i] != s2[i]) j < 0 ? j = i : (swap(s1[j], s1[i]),++c);
        return s1 == s2;
    }