From f26fe3244096d157e2eb8ea777cdbb4ba1b65d60 Mon Sep 17 00:00:00 2001
From: Xu Shaohua <shaohua@biofan.org>
Date: Thu, 9 May 2024 21:44:38 +0800
Subject: [PATCH] leetcode: Add 0973

---
 .../Cargo.toml                                |   7 +
 .../0973.k-closest-points-to-origin/index.md  |   4 +
 .../src/main.rs                               | 122 ++++++++++++++++++
 3 files changed, 133 insertions(+)
 create mode 100644 src/leetcode/0973.k-closest-points-to-origin/Cargo.toml
 create mode 100644 src/leetcode/0973.k-closest-points-to-origin/index.md
 create mode 100644 src/leetcode/0973.k-closest-points-to-origin/src/main.rs

diff --git a/src/leetcode/0973.k-closest-points-to-origin/Cargo.toml b/src/leetcode/0973.k-closest-points-to-origin/Cargo.toml
new file mode 100644
index 00000000..e994666a
--- /dev/null
+++ b/src/leetcode/0973.k-closest-points-to-origin/Cargo.toml
@@ -0,0 +1,7 @@
+[package]
+name = "lc-0973-k-closest-points-to-origin"
+version = "0.1.0"
+edition = "2021"
+publish = false
+
+[dependencies]
diff --git a/src/leetcode/0973.k-closest-points-to-origin/index.md b/src/leetcode/0973.k-closest-points-to-origin/index.md
new file mode 100644
index 00000000..77a618ba
--- /dev/null
+++ b/src/leetcode/0973.k-closest-points-to-origin/index.md
@@ -0,0 +1,4 @@
+
+# 
+
+[问题描述](../problems/)
diff --git a/src/leetcode/0973.k-closest-points-to-origin/src/main.rs b/src/leetcode/0973.k-closest-points-to-origin/src/main.rs
new file mode 100644
index 00000000..7fa94aa8
--- /dev/null
+++ b/src/leetcode/0973.k-closest-points-to-origin/src/main.rs
@@ -0,0 +1,122 @@
+// Copyright (c) 2024 Xu Shaohua <shaohua@biofan.org>. All rights reserved.
+// Use of this source is governed by General Public License that can be found
+// in the LICENSE file.
+
+use std::cmp::{Ord, Ordering, PartialOrd};
+use std::collections::BinaryHeap;
+
+// Priority Queue
+pub fn k_closest1(points: Vec<Vec<i32>>, k: i32) -> Vec<Vec<i32>> {
+    assert!(k >= 1 && (k as usize) <= points.len());
+
+    #[derive(Debug, Clone, Eq, PartialEq)]
+    struct Entry {
+        dist: i64,
+        point: Vec<i32>,
+    }
+    impl PartialOrd for Entry {
+        fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
+            Some(self.cmp(other))
+        }
+    }
+
+    impl Ord for Entry {
+        fn cmp(&self, other: &Self) -> Ordering {
+            self.dist.cmp(&other.dist)
+        }
+    }
+
+    // 构造优先级队列.
+    let k = k as usize;
+    let mut heap: BinaryHeap<Entry> = BinaryHeap::with_capacity(k + 1);
+    for point in points {
+        // 这里, 不需要求平方根, 因为不够精确, 也没必要, 只需要计算出 x*x + y*y 的值即可.
+        // 为了处理整数溢出, 先转成 i64.
+        let x = point[0] as i64;
+        let y = point[1] as i64;
+        let dist: i64 = x * x + y * y;
+        //println!("dist: {dist}, point: {point:?}");
+        heap.push(Entry { dist, point });
+        if heap.len() > k {
+            heap.pop();
+        }
+    }
+
+    let mut out = Vec::with_capacity(k);
+    while let Some(top_entry) = heap.pop() {
+        out.push(top_entry.point);
+    }
+    // 再次排序.
+    out.reverse();
+    out
+}
+
+// 有序数组
+pub fn k_closest2(points: Vec<Vec<i32>>, k: i32) -> Vec<Vec<i32>> {
+    assert!(k >= 1 && (k as usize) <= points.len());
+
+    // 构造优先级队列.
+    let k = k as usize;
+    let mut point_dists: Vec<(i64, Vec<i32>)> = points
+        .into_iter()
+        .map(|point| {
+            // 这里, 不需要求平方根, 因为不够精确, 也没必要, 只需要计算出 x*x + y*y 的值即可.
+            // 为了处理整数溢出, 先转成 i64.
+            let x = point[0] as i64;
+            let y = point[1] as i64;
+            let dist: i64 = x * x + y * y;
+            (dist, point)
+        })
+        .collect();
+    // 根据 dist 升序排列
+    point_dists.sort_by(|a, b| a.0.cmp(&b.0));
+
+    // 取前k个元素
+    point_dists
+        .into_iter()
+        .take(k)
+        .map(|(_dist, point)| point)
+        .collect()
+}
+
+// TODO(Shaohua): Quickselect
+
+pub type SolutionFn = fn(Vec<Vec<i32>>, i32) -> Vec<Vec<i32>>;
+
+fn check_solution(func: SolutionFn) {
+    let points = vec![vec![1, 3], vec![-2, 2]];
+    let k = 1;
+    assert_eq!(func(points, k), vec![vec![-2, 2]]);
+
+    let points = vec![vec![3, 3], vec![5, -1], vec![-2, 4]];
+    let k = 1;
+    assert_eq!(func(points, k), vec![vec![3, 3]]);
+
+    let points = vec![vec![3, 3], vec![5, -1], vec![-2, 4]];
+    let k = 2;
+    assert_eq!(func(points, k), vec![vec![3, 3], vec![-2, 4]]);
+
+    let points = vec![vec![9997, 9997], vec![9996, 9998]];
+    let k = 1;
+    assert_eq!(func(points, k), vec![vec![9997, 9997]]);
+}
+
+fn main() {
+    check_solution(k_closest1);
+    check_solution(k_closest2);
+}
+
+#[cfg(test)]
+mod tests {
+    use super::{check_solution, k_closest1, k_closest2};
+
+    #[test]
+    fn test_k_closest1() {
+        check_solution(k_closest1);
+    }
+
+    #[test]
+    fn test_k_closest2() {
+        check_solution(k_closest2);
+    }
+}