From 9e340501d5de24a8b75ffc328027b31c019784c8 Mon Sep 17 00:00:00 2001 From: m4siri Date: Wed, 3 Dec 2025 22:28:35 +0545 Subject: solve: 07_reverse-integer i really enjoyed solving this one. mfw when i saw other's 0ms solution. --- 07_reverse-integer/src/main.rs | 44 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 44 insertions(+) create mode 100644 07_reverse-integer/src/main.rs (limited to '07_reverse-integer/src') diff --git a/07_reverse-integer/src/main.rs b/07_reverse-integer/src/main.rs new file mode 100644 index 0000000..2fb80c4 --- /dev/null +++ b/07_reverse-integer/src/main.rs @@ -0,0 +1,44 @@ +fn main() { + dbg!(Solution::reverse(1534236469)); +} + +struct Solution(()); + +impl Solution { + pub fn reverse(x: i32) -> i32 { + let n = if x < 0 { x * -1 } else { x }; + + if let Some(i) = Self::invert(n as u32, 0).0 { + let t: u32 = 1 << 31; + + if (i & t) == t { + return 0; + } + + if x < 0 { + return i as i32 * -1; + } + + return i as i32; + } + + 0 + } + + fn invert(n: u32, pow: u32) -> (Option, u32) { + if n < 10 { + return (Some(n), pow + 1); + } + + let m = n % 10; + let d = (n - m) / 10; + let c = Self::invert(d, pow); + + if let Some(inner) = c.0 + && let Some(m) = m.checked_mul(10_u32.pow(c.1)) + { + return (Some(m + inner), c.1 + 1); + } + (None, 0) + } +} -- cgit v1.2.3