From a296a13e73842815d27e5c66d7915e44aee945bc Mon Sep 17 00:00:00 2001
From: SquidSpirit <squid@squidspirit.com>
Date: Wed, 20 Aug 2025 00:01:04 +0800
Subject: [PATCH] feat: 29_divide_two_integer

---
 29_divide_two_integer/Cargo.lock |  7 ++++
 29_divide_two_integer/Cargo.toml |  6 ++++
 29_divide_two_integer/src/lib.rs | 58 ++++++++++++++++++++++++++++++++
 3 files changed, 71 insertions(+)
 create mode 100644 29_divide_two_integer/Cargo.lock
 create mode 100644 29_divide_two_integer/Cargo.toml
 create mode 100644 29_divide_two_integer/src/lib.rs

diff --git a/29_divide_two_integer/Cargo.lock b/29_divide_two_integer/Cargo.lock
new file mode 100644
index 0000000..1968a90
--- /dev/null
+++ b/29_divide_two_integer/Cargo.lock
@@ -0,0 +1,7 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 4
+
+[[package]]
+name = "divide_two_integer"
+version = "0.1.0"
diff --git a/29_divide_two_integer/Cargo.toml b/29_divide_two_integer/Cargo.toml
new file mode 100644
index 0000000..803d5f2
--- /dev/null
+++ b/29_divide_two_integer/Cargo.toml
@@ -0,0 +1,6 @@
+[package]
+name = "divide_two_integer"
+version = "0.1.0"
+edition = "2024"
+
+[dependencies]
diff --git a/29_divide_two_integer/src/lib.rs b/29_divide_two_integer/src/lib.rs
new file mode 100644
index 0000000..eaaa4bc
--- /dev/null
+++ b/29_divide_two_integer/src/lib.rs
@@ -0,0 +1,58 @@
+pub struct Solution;
+
+impl Solution {
+    /// - Dividend = Quotient * Divisor + Rem
+    /// - Rem < Divisor
+    pub fn divide(mut dividend: i32, mut divisor: i32) -> i32 {
+        if divisor == i32::MIN {
+            return if dividend == i32::MIN { 1 } else { 0 };
+        }
+
+        let is_positive = dividend.is_positive() == divisor.is_positive();
+
+        let mut is_overflow = false;
+        if dividend == i32::MIN {
+            is_overflow = true;
+            dividend += 1;
+        }
+
+        dividend = dividend.abs();
+        divisor = divisor.abs();
+
+        if dividend < divisor {
+            return 0;
+        }
+
+        let mut quotient = 0;
+        let mut rem;
+        loop {
+            let mut exp = 1;
+            while divisor << exp <= dividend && divisor << exp > 0 {
+                exp += 1;
+            }
+            exp -= 1;
+
+            quotient += 1 << exp;
+            rem = dividend - (divisor << exp);
+            if rem < divisor {
+                break;
+            }
+
+            dividend = rem;
+        }
+
+        if is_overflow && rem + 1 >= divisor {
+            if is_positive {
+                if quotient == i32::MAX {
+                    quotient
+                } else {
+                    quotient + 1
+                }
+            } else {
+                -quotient - 1
+            }
+        } else {
+            if is_positive { quotient } else { -quotient }
+        }
+    }
+}