LeetCode Entry

717. 1-bit and 2-bit Characters

18.11.2025 easy 2025 kotlin rust

Is '0' last from characters '0','10','11' concatenation

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Problem TLDR

Is ‘0’ last from characters ‘0’,’10’,’11’ concatenation #easy

Intuition

I had to start with DP: in each i position if b[i] zero go next, otherwise go next->next. Then it is just a linear solution without a choice.

Approach

• optimization: go from back

Complexity

• Time complexity: \(O(n)\)

• Space complexity: \(O(1)\)

Code

// 0ms
    fun isOneBitCharacter(b: IntArray): Boolean {
        var i = b.size - 2
        while (i >= 0 && b[i] > 0) i -= b[i]
        return (b.size - i) % 2 < 1
    }

// 0ms
    pub fn is_one_bit_character(b: Vec<i32>) -> bool {
        b[..b.len()-1].split(|&x|x<1).last().unwrap().len()%2<1
    }