LeetCode Entry

1323. Maximum 69 Number

16.08.2025 easy 2025 kotlin rust

Bigger number by replacing 6 to 9

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Problem TLDR

Bigger number by replacing 6 to 9 #easy

Intuition

The simpliest way is to convert to char array, replace first, then stop.

Approach

  • let’s explore other unusual ways

Complexity

  • Time complexity: \(O(1)\)

  • Space complexity: \(O(1)\)

Code


// 7ms
    fun maximum69Number (n: Int) =
    "$n".replaceFirst('6', '9').toInt()



// 12ms
    fun maximum69Number (n: Int) =
    n + 3 * (setOf(1000, 100, 10, 1).firstOrNull { n/it%9>0 }?:0)



// 0ms
    pub fn maximum69_number(n: i32) -> i32 {
        n + 3 * [1000, 100, 10, 1].iter().find(|&&p| n/p%10==6).unwrap_or(&0)
    }



// 0ms
    int maximum69Number (int n) {
        for (int p = 1000; p; p /= 10)
            if (n/p%10 == 6) return n + 3*p;
        return n;
    }



// 0ms
    maximum69Number = lambda _, n: int(str(n).replace('6','9',1))