Some leetcode problems

.gitignore

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+/target

Cargo.lock

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+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 4
+
+[[package]]
+name = "leetcode"
+version = "0.1.0"

Cargo.toml

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+[package]
+name = "leetcode"
+version = "0.1.0"
+edition = "2024"
+
+[dependencies]

src/lib.rs

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+pub mod p1;
+pub mod p2;
+pub mod p238;
+
+pub struct Solution;
+
+// Definition for singly-linked list.
+#[derive(PartialEq, Eq, Clone, Debug)]
+pub struct ListNode {
+    pub val: i32,
+    pub next: Option<Box<ListNode>>,
+}
+
+impl ListNode {
+    #[inline]
+    fn _new(val: i32) -> Self {
+        ListNode { next: None, val }
+    }
+}

src/p1.rs

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+use crate::Solution;
+
+impl Solution {
+    pub fn two_sum(nums: Vec<i32>, target: i32) -> Vec<i32> {
+        for (i, e1) in nums.clone().iter().enumerate() {
+            for (j, e2) in nums[i + 1..].iter().enumerate() {
+                if e1 + e2 == target {
+                    return vec![i as i32, (i + (j + 1)) as i32];
+                }
+            }
+        }
+        unreachable!() // there is exactly one solution
+    }
+}
+
+#[test]
+pub fn test_two_sum_1() {
+    assert_eq!(Solution::two_sum(vec![2, 7, 11, 15], 9), vec![0, 1]);
+}
+
+#[test]
+pub fn test_two_sum_2() {
+    assert_eq!(Solution::two_sum(vec![3, 2, 4], 6), vec![1, 2]);
+}
+
+#[test]
+pub fn test_two_sum_3() {
+    assert_eq!(Solution::two_sum(vec![3, 3], 6), vec![0, 1]);
+}

src/p2.rs

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+use crate::{ListNode, Solution};
+
+// Definition for singly-linked list.
+
+impl Solution {
+    pub fn add_two_numbers(
+        l1: Option<Box<ListNode>>,
+        l2: Option<Box<ListNode>>,
+    ) -> Option<Box<ListNode>> {
+        Solution::add_two_numbers_rec(l1, l2, 0)
+    }
+
+    pub fn add_two_numbers_rec(
+        l1: Option<Box<ListNode>>,
+        l2: Option<Box<ListNode>>,
+        carry: i32,
+    ) -> Option<Box<ListNode>> {
+        Option::Some(Box::new(match (l1, l2) {
+            (None, None) => {
+                if carry > 0 {
+                    ListNode {
+                        val: 1,
+                        next: Option::None,
+                    }
+                } else {
+                    return Option::None;
+                }
+            }
+            (None, Some(a)) => {
+                let mut sum = a.val + carry;
+                let mut new_carry = 0;
+                if sum > 9 {
+                    new_carry = 1;
+                    sum -= 10;
+                }
+                ListNode {
+                    val: sum,
+                    next: Solution::add_two_numbers_rec(Option::None, a.next, new_carry),
+                }
+            }
+            (Some(a), None) => {
+                let mut sum = a.val + carry;
+                let mut new_carry = 0;
+                if sum > 9 {
+                    new_carry = 1;
+                    sum -= 10;
+                }
+                ListNode {
+                    val: sum,
+                    next: Solution::add_two_numbers_rec(a.next, Option::None, new_carry),
+                }
+            }
+            (Some(a), Some(b)) => {
+                let mut sum = a.val + b.val + carry;
+                let mut new_carry = 0;
+                if sum > 9 {
+                    new_carry = 1;
+                    sum -= 10;
+                }
+                ListNode {
+                    val: sum,
+                    next: Solution::add_two_numbers_rec(a.next, b.next, new_carry),
+                }
+            }
+        }))
+    }
+}
+
+#[test]
+pub fn test_add_two_numbers_1() {
+    assert_eq!(
+        i32_from_list_node(Solution::add_two_numbers(
+            list_node_from_array(&[2, 4, 3]),
+            list_node_from_array(&[5, 6, 4])
+        )),
+        807
+    );
+}
+
+#[test]
+pub fn test_add_two_numbers_2() {
+    assert_eq!(
+        i32_from_list_node(Solution::add_two_numbers(
+            list_node_from_array(&[0]),
+            list_node_from_array(&[0])
+        )),
+        0
+    );
+}
+
+#[test]
+pub fn test_add_two_numbers_3() {
+    assert_eq!(
+        i32_from_list_node(Solution::add_two_numbers(
+            list_node_from_array(&[9, 9, 9, 9, 9, 9, 9]),
+            list_node_from_array(&[9, 9, 9, 9])
+        )),
+        10009998
+    );
+}
+
+pub fn list_node_from_array(arr: &[i32]) -> Option<Box<ListNode>> {
+    Option::Some(Box::new(ListNode {
+        val: arr[0],
+        next: if arr.len() > 1 {
+            list_node_from_array(&arr[1..])
+        } else {
+            Option::None
+        },
+    }))
+}
+
+pub fn i32_from_list_node(l: Option<Box<ListNode>>) -> i32 {
+    if let Some(a) = l {
+        a.val + i32_from_list_node(a.next) * 10
+    } else {
+        0
+    }
+}

src/p238.rs

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+use crate::Solution;
+
+impl Solution {
+    pub fn product_except_self(nums: Vec<i32>) -> Vec<i32> {
+        let mut res = nums.clone();
+        let mut acc = 1;
+        for i in 0..nums.len() - 1 {
+            acc *= nums[i];
+            res[i + 1] = acc;
+        }
+        acc = 1;
+        for i in (1..nums.len()).rev() {
+            acc *= nums[i];
+            res[i - 1] *= acc;
+        }
+        res
+    }
+}
+
+#[test]
+pub fn test_product_except_self_1() {
+    assert_eq!(
+        Solution::product_except_self(vec![1, 2, 3, 4]),
+        vec![24, 12, 8, 6]
+    );
+}
+
+#[test]
+pub fn test_product_except_self_2() {
+    assert_eq!(
+        Solution::product_except_self(vec![-1, 1, 0, -3, 3]),
+        vec![0, 0, 9, 0, 0]
+    );
+}