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2 | 2 |
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3 | 3 | import java.util.Arrays;
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4 | 4 |
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5 |
| -/**259. 3Sum Smaller |
6 |
| -
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7 |
| -Given an array of n integers nums and a target, find the number of index triplets i, j, k with 0 <= i < j < k < n that satisfy the condition nums[i] + nums[j] + nums[k] < target. |
8 |
| -
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9 |
| -For example, given nums = [-2, 0, 1, 3], and target = 2. |
10 |
| -
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11 |
| -Return 2. Because there are two triplets which sums are less than 2: |
12 |
| -
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13 |
| -[-2, 0, 1] |
14 |
| -[-2, 0, 3] |
15 |
| -
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16 |
| -Follow up: |
17 |
| -Could you solve it in O(n2) runtime? */ |
18 | 5 | public class _259 {
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19 | 6 |
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20 |
| - /**Basically, very similar to 3Sum, but the key is that you'll have to add result by (right-left), not just increment result by 1!*/ |
21 |
| - public int threeSumSmaller(int[] nums, int target) { |
22 |
| - if (nums == null || nums.length == 0) { |
23 |
| - return 0; |
24 |
| - } |
25 |
| - int result = 0; |
26 |
| - Arrays.sort(nums); |
27 |
| - for (int i = 0; i < nums.length - 2; i++) { |
28 |
| - int left = i + 1; |
29 |
| - int right = nums.length - 1; |
30 |
| - while (left < right) { |
31 |
| - int sum = nums[i] + nums[left] + nums[right]; |
32 |
| - if (sum < target) { |
33 |
| - result += right - left;//this line is key! |
34 |
| - left++; |
35 |
| - } else { |
36 |
| - right--; |
| 7 | + public static class Solution1 { |
| 8 | + /** |
| 9 | + * Basically, very similar to 3Sum, but the key is that you'll have to add result by (right-left), not just increment result by 1! |
| 10 | + */ |
| 11 | + public int threeSumSmaller(int[] nums, int target) { |
| 12 | + if (nums == null || nums.length == 0) { |
| 13 | + return 0; |
| 14 | + } |
| 15 | + int result = 0; |
| 16 | + Arrays.sort(nums); |
| 17 | + for (int i = 0; i < nums.length - 2; i++) { |
| 18 | + int left = i + 1; |
| 19 | + int right = nums.length - 1; |
| 20 | + while (left < right) { |
| 21 | + int sum = nums[i] + nums[left] + nums[right]; |
| 22 | + if (sum < target) { |
| 23 | + result += right - left;//this line is key! |
| 24 | + left++; |
| 25 | + } else { |
| 26 | + right--; |
| 27 | + } |
37 | 28 | }
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38 | 29 | }
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| 30 | + return result; |
39 | 31 | }
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40 |
| - return result; |
41 | 32 | }
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42 | 33 | }
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