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1 | 1 | package g0301_0400.s0373_find_k_pairs_with_smallest_sums;
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2 | 2 |
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3 | 3 | // #Medium #Array #Heap_Priority_Queue #Top_Interview_150_Heap
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4 |
| -// #2025_03_09_Time_0_ms_(100.00%)_Space_57.66_MB_(90.88%) |
| 4 | +// #2025_03_09_Time_27_ms_(90.23%)_Space_58.22_MB_(77.32%) |
5 | 5 |
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6 |
| -import java.util.AbstractList; |
7 | 6 | import java.util.ArrayList;
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8 |
| -import java.util.Arrays; |
9 | 7 | import java.util.List;
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| 8 | +import java.util.PriorityQueue; |
10 | 9 |
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11 | 10 | public class Solution {
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12 |
| - public List<List<Integer>> kSmallestPairs(int[] nums1, int[] nums2, int k) { |
13 |
| - return new AbstractList<List<Integer>>() { |
14 |
| - private List<List<Integer>> pairs; |
15 |
| - |
16 |
| - @Override |
17 |
| - public List<Integer> get(int index) { |
18 |
| - init(); |
19 |
| - return pairs.get(index); |
20 |
| - } |
21 |
| - |
22 |
| - @Override |
23 |
| - public int size() { |
24 |
| - init(); |
25 |
| - return pairs.size(); |
26 |
| - } |
27 |
| - |
28 |
| - private void load() { |
29 |
| - int n = nums1.length; |
30 |
| - int m = nums2.length; |
31 |
| - int left = nums1[0] + nums2[0]; |
32 |
| - int right = nums1[n - 1] + nums2[m - 1]; |
33 |
| - int middle; |
34 |
| - |
35 |
| - while (left <= right) { |
36 |
| - middle = (left + right) / 2; |
37 |
| - long count = getCount(nums1, nums2, middle, k); |
38 |
| - if (count < k) { |
39 |
| - left = middle + 1; |
40 |
| - } else if (count > k) { |
41 |
| - right = middle - 1; |
42 |
| - } else { |
43 |
| - left = middle; |
44 |
| - break; |
45 |
| - } |
46 |
| - } |
47 |
| - getPairs(nums1, nums2, left, k); |
48 |
| - } |
49 |
| - |
50 |
| - private long getCount(int[] nums1, int[] nums2, int goal, int k) { |
51 |
| - int prevRight = nums2.length - 1; |
52 |
| - int count = 0; |
53 |
| - |
54 |
| - for (int i = 0; i < nums1.length && nums1[i] + nums2[0] <= goal; i++) { |
55 |
| - int left = 0; |
56 |
| - int right = prevRight; |
57 |
| - int position = -1; |
58 |
| - while (left <= right) { |
59 |
| - int middle = (right + left) / 2; |
60 |
| - int sum = nums1[i] + nums2[middle]; |
61 |
| - if (sum <= goal) { |
62 |
| - position = middle; |
63 |
| - left = middle + 1; |
64 |
| - } else { |
65 |
| - right = middle - 1; |
66 |
| - } |
67 |
| - } |
68 |
| - if (position >= 0) { |
69 |
| - count += position + 1; |
70 |
| - prevRight = position; |
71 |
| - } |
72 |
| - if (count > k) { |
73 |
| - return count; |
74 |
| - } |
75 |
| - } |
76 |
| - return count; |
77 |
| - } |
78 |
| - |
79 |
| - private void getPairs(int[] nums1, int[] nums2, int sum, int k) { |
80 |
| - pairs = new ArrayList<>(); |
81 |
| - for (int item : nums1) { |
82 |
| - for (int j = 0; j < nums2.length && item + nums2[j] < sum; j++) { |
83 |
| - pairs.add(Arrays.asList(item, nums2[j])); |
84 |
| - } |
85 |
| - } |
86 |
| - for (int value : nums1) { |
87 |
| - for (int j = 0; |
88 |
| - j < nums2.length && value + nums2[j] <= sum && pairs.size() < k; |
89 |
| - j++) { |
90 |
| - if (value + nums2[j] == sum) { |
91 |
| - pairs.add(Arrays.asList(value, nums2[j])); |
92 |
| - } |
93 |
| - } |
94 |
| - } |
95 |
| - } |
| 11 | + private static class Node { |
| 12 | + long sum; |
| 13 | + List<Integer> al; |
| 14 | + int index; |
| 15 | + |
| 16 | + Node(int index, int num1, int num2) { |
| 17 | + this.sum = (long) num1 + (long) num2; |
| 18 | + this.al = new ArrayList<>(); |
| 19 | + this.al.add(num1); |
| 20 | + this.al.add(num2); |
| 21 | + this.index = index; |
| 22 | + } |
| 23 | + } |
96 | 24 |
|
97 |
| - public void init() { |
98 |
| - if (null == pairs) { |
99 |
| - load(); |
100 |
| - } |
| 25 | + public List<List<Integer>> kSmallestPairs(int[] nums1, int[] nums2, int k) { |
| 26 | + PriorityQueue<Node> queue = new PriorityQueue<>((a, b) -> a.sum < b.sum ? -1 : 1); |
| 27 | + List<List<Integer>> res = new ArrayList<>(); |
| 28 | + for (int i = 0; i < nums1.length && i < k; i++) { |
| 29 | + queue.add(new Node(0, nums1[i], nums2[0])); |
| 30 | + } |
| 31 | + for (int i = 1; i <= k && !queue.isEmpty(); i++) { |
| 32 | + Node cur = queue.poll(); |
| 33 | + res.add(cur.al); |
| 34 | + int next = cur.index; |
| 35 | + int lastNum1 = cur.al.get(0); |
| 36 | + if (next + 1 < nums2.length) { |
| 37 | + queue.add(new Node(next + 1, lastNum1, nums2[next + 1])); |
101 | 38 | }
|
102 |
| - }; |
| 39 | + } |
| 40 | + return res; |
103 | 41 | }
|
104 | 42 | }
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