leetcode: Add 0532

src/SUMMARY.md

@@ -123,6 +123,7 @@
     - [0401-0500](leetcode/orders/0401-0500.md)
         - [0485. 最大连续1的个数 Max Consecutive Ones](leetcode/0485.max-consecutive-ones/index.md)
     - [0501-0600](leetcode/orders/0501-0600.md)
+        - [0532.数组中的数对 K-diff Pairs in an Array](leetcode/0532.k-diff-pairs-in-an-array/index.md)
     - [0601-0700](leetcode/orders/0601-0700.md)
         - [0680. 验证回文串 II Valid Palindrome II](leetcode/0680.valid-palindrome-ii/index.md)
     - [0701-0800](leetcode/orders/0701-0800.md)

src/leetcode/0349.intersection-of-two-arrays/index.md

@@ -2,7 +2,7 @@
 
 [问题描述](../problems/0349.intersection-of-two-arrays/content.html)
 
-这个问题的解法就比较多了.
+这是一个搜索问题, 这个问题的解法就比较多了.
 
 ## 并行双指针
 
@@ -75,4 +75,4 @@ C++ 这样的语言在标准库里自带了 BitSet, 但在 Rust 标准库里却
 
 ## 相关问题
 
-- [0350. 两个数组的交集 II Intersection of Two Arrays II](../0350.intersection-of-two-arrays-ii/index.md)
+- [0350. 两个数组的交集 II Intersection of Two Arrays II](../0350.intersection-of-two-arrays-ii/index.md)

src/leetcode/0532.k-diff-pairs-in-an-array/Cargo.toml

@@ -0,0 +1,7 @@
+[package]
+name = "lc-0532-k-diff-pairs-in-an-array"
+version = "0.1.0"
+edition = "2021"
+publish = false
+
+[dependencies]

src/leetcode/0532.k-diff-pairs-in-an-array/index.md

@@ -0,0 +1,3 @@
+# 0532.数组中的数对 K-diff Pairs in an Array
+
+[问题描述](../problems/0532.k-diff-pairs-in-an-array/content.html)

src/leetcode/0532.k-diff-pairs-in-an-array/src/main.rs

@@ -0,0 +1,208 @@
+// Copyright (c) 2024 Xu Shaohua <[email protected]>. All rights reserved.
+// Use of this source is governed by General Public License that can be found
+// in the LICENSE file.
+
+use std::collections::{HashMap, HashSet};
+
+// 哈稀表
+pub fn find_pairs1(nums: Vec<i32>, k: i32) -> i32 {
+    assert!(!nums.is_empty());
+
+    let mut map = HashMap::new();
+    for num in &nums {
+        map.entry(num).and_modify(|count| *count += 1).or_insert(1);
+    }
+
+    let mut set = HashSet::new();
+    for &num in &nums {
+        // k = diff - num;
+        // diff1 >= num
+        let diff1 = num + k;
+        if let Some(count) = map.get(&diff1) {
+            if diff1 > num {
+                set.insert(vec![num, diff1]);
+            } else if diff1 == num {
+                if *count > 1 {
+                    set.insert(vec![num, diff1]);
+                }
+            }
+        }
+
+        // k = num - diff;
+        // diff2 <= num
+        let diff2 = num - k;
+        if let Some(count) = map.get(&diff2) {
+            if diff2 < num {
+                set.insert(vec![diff2, num]);
+            } else if diff2 == num {
+                if *count > 1 {
+                    set.insert(vec![num, diff2]);
+                }
+            }
+        }
+    }
+
+    set.len() as i32
+}
+
+// 二分查找
+pub fn find_pairs2(nums: Vec<i32>, k: i32) -> i32 {
+    assert!(!nums.is_empty());
+
+    // 先排序
+    let mut nums = nums;
+    nums.sort();
+    let mut set = HashSet::new();
+
+    for i in 0..(nums.len() - 1) {
+        let val = nums[i] + k;
+        if let Ok(_val_index) = nums[i + 1..].binary_search(&val) {
+            set.insert((nums[i], val));
+        }
+    }
+
+    set.len() as i32
+}
+
+// 快慢型双指针
+pub fn find_pairs3(nums: Vec<i32>, k: i32) -> i32 {
+    assert!(!nums.is_empty());
+
+    // 先排序
+    let mut nums = nums;
+    nums.sort();
+
+    let mut fast = 0;
+    let len = nums.len();
+    let mut count = 0;
+
+    // 遍历数组
+    while fast < len {
+        let curr_val = nums[fast];
+        let expected_val = curr_val + k;
+        // 当前值和期待值是否相等, 即 k 是否为0.
+        if expected_val == curr_val {
+            // 只保留两个重复元素, 跳过其它的.
+            let mut added = false;
+            while fast + 1 < len && curr_val == nums[fast + 1] {
+                if !added {
+                    count += 1;
+                    added = true;
+                }
+                fast += 1;
+            }
+        } else {
+            // 跳过所有重复元素
+            while fast + 1 < len && curr_val == nums[fast + 1] {
+                fast += 1;
+            }
+            // 使用二分查找法在后面的元素里搜索 `expected_val`.
+            if fast + 1 < len && nums[fast + 1..].binary_search(&expected_val).is_ok() {
+                count += 1;
+            }
+        }
+
+        // 指针向前走一步
+        fast += 1;
+    }
+
+    count
+}
+
+// 根据 k == 0 做优化
+pub fn find_pairs4(nums: Vec<i32>, k: i32) -> i32 {
+    assert!(!nums.is_empty());
+
+    // 先排序
+    let mut nums = nums;
+    nums.sort();
+    let mut count = 0;
+    let mut fast = 0;
+
+    if k == 0 {
+        let len = nums.len();
+
+        // 遍历数组
+        while fast < len {
+            let curr_val = nums[fast];
+            // 只保留两个重复元素, 跳过其它的.
+            if fast + 1 < len && curr_val == nums[fast + 1] {
+                count += 1;
+                fast += 1;
+            }
+            while fast + 1 < len && curr_val == nums[fast + 1] {
+                fast += 1;
+            }
+
+            // 指针向前走一步
+            fast += 1;
+        }
+    } else {
+        // 去掉重复元素
+        nums.dedup();
+        let len = nums.len();
+
+        // 遍历数组
+        while fast < len {
+            let curr_val = nums[fast];
+            let expected_val = curr_val + k;
+            // 使用二分查找法在后面的元素里搜索 `expected_val`.
+            if fast + 1 < len && nums[fast + 1..].binary_search(&expected_val).is_ok() {
+                count += 1;
+            }
+
+            // 指针向前走一步
+            fast += 1;
+        }
+    }
+
+    count
+}
+
+pub type SolutionFn = fn(Vec<i32>, i32) -> i32;
+
+fn check_solution(func: SolutionFn) {
+    let nums = vec![3, 1, 4, 1, 5];
+    let k = 2;
+    assert_eq!(func(nums, k), 2);
+
+    let nums = vec![1, 2, 3, 4, 5];
+    let k = 1;
+    assert_eq!(func(nums, k), 4);
+
+    let nums = vec![1, 3, 1, 5, 4];
+    let k = 0;
+    assert_eq!(func(nums, k), 1);
+}
+
+fn main() {
+    check_solution(find_pairs1);
+    check_solution(find_pairs2);
+    check_solution(find_pairs3);
+    check_solution(find_pairs4);
+}
+
+#[cfg(test)]
+mod tests {
+    use super::{check_solution, find_pairs1, find_pairs2, find_pairs3, find_pairs4};
+
+    #[test]
+    fn test_find_pairs1() {
+        check_solution(find_pairs1);
+    }
+
+    #[test]
+    fn test_find_pairs2() {
+        check_solution(find_pairs2);
+    }
+
+    #[test]
+    fn test_find_pairs3() {
+        check_solution(find_pairs3);
+    }
+
+    #[test]
+    fn test_find_pairs4() {
+        check_solution(find_pairs4);
+    }
+}

src/leetcode/tags/binary-search.md

@@ -2,6 +2,10 @@
 
 ## 容易
 
+1. [0349. 两个数组的交集 Intersection of Two Arrays](../0349.intersection-of-two-arrays/index.md)
+
+TODO:
+
 - [69. x 的平方根](https://leetcode.com/problems/sqrtx)
 - [167. 两数之和 II - 输入有序数组](https://leetcode.com/problems/two-sum-ii-input-array-is-sorted)
 - [278. 第一个错误的版本](https://leetcode.com/problems/first-bad-version)
@@ -16,6 +20,11 @@
 
 ## 中等
 
+1. [0167. 两数之和 II - 输入有序数组 Two Sum II - Input Array Is Sorted](../0167.two-sum-ii-input-array-is-sorted/index.md)
+2. [0532.数组中的数对 K-diff Pairs in an Array](../0532.k-diff-pairs-in-an-array/index.md)
+
+TODO:
+
 - [29. 两数相除](https://leetcode.com/problems/divide-two-integers)
 - [33. Search in Rotated Sorted Array](https://leetcode.com/problems/search-in-rotated-sorted-array/description/)
 - [34. 在排序数组中查找元素的第一个和最后一个位置](https://leetcode.com/problems/find-first-and-last-position-of-element-in-sorted-array)

src/leetcode/tags/hash-table.md

@@ -23,6 +23,11 @@
 
 ## 中等
 
+1. [0167. 两数之和 II - 输入有序数组 Two Sum II - Input Array Is Sorted](../0167.two-sum-ii-input-array-is-sorted/index.md)
+2. [0532.数组中的数对 K-diff Pairs in an Array](../0532.k-diff-pairs-in-an-array/index.md)
+
+TODO:
+
 - [3.无重复字符的最长子串](https://leetcode.com/problems/longest-substring-without-repeating-characters)
 - [215. 数组中的第K个最大元素](https://leetcode.com/problems/kth-largest-element-in-an-array)
 - [347. 前 K 个高频元素](https://leetcode.com/problems/top-k-frequent-elements)

src/leetcode/tags/two-pointers.md

@@ -24,6 +24,7 @@ TODO:
 2. [0015. 三数之和 3Sum](../0015.3sum/index.md)
 3. [0080. 删除排序数组中的重复项 II Remove Duplicates from Sorted Array II](../0080.remove-duplicates-from-sorted-array-ii/index.md)
 4. [0167. 两数之和 II - 输入有序数组 Two Sum II - Input Array Is Sorted](../0167.two-sum-ii-input-array-is-sorted/index.md)
+5. [0532.数组中的数对 K-diff Pairs in an Array](../0532.k-diff-pairs-in-an-array/index.md)
 
 TODO:
 
@@ -32,6 +33,5 @@ TODO:
 3. [142. 环形链表 II](https://leetcode.com/problems/linked-list-cycle-ii)
 4. [443. 压缩字符串](https://leetcode.com/problems/string-compression)
 5. [524. 通过删除字母匹配到字典里最长单词](https://leetcode.com/problems/longest-word-in-dictionary-through-deleting)
-6. [532.数组中的数对](https://leetcode.com/problems/k-diff-pairs-in-an-array)
-7. [986. 区间列表的交集](https://leetcode.com/problems/interval-list-intersections)
-8. [1498. 满足条件的子序列数目](https://leetcode.com/problems/number-of-subsequences-that-satisfy-the-given-sum-condition)
+6. [986. 区间列表的交集](https://leetcode.com/problems/interval-list-intersections)
+7. [1498. 满足条件的子序列数目](https://leetcode.com/problems/number-of-subsequences-that-satisfy-the-given-sum-condition)