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| 1 | +class Solution { |
| 2 | + fun fourSum(nums: IntArray, target: Int): List<List<Int>> { |
| 3 | + val target = target.toLong() |
| 4 | + |
| 5 | + nums.sort() |
| 6 | + |
| 7 | + val result = mutableListOf<List<Int>>() |
| 8 | + |
| 9 | + var prevA: Int? = null |
| 10 | + var prevB: Int? = null |
| 11 | + var prevC: Int? = null |
| 12 | + |
| 13 | + for (a in nums.indices) { |
| 14 | + if (nums[a] == prevA) { |
| 15 | + continue |
| 16 | + } |
| 17 | + |
| 18 | + for (b in (a + 1)..nums.lastIndex) { |
| 19 | + if (nums[a] == prevA && nums[b] == prevB) { |
| 20 | + continue |
| 21 | + } |
| 22 | + |
| 23 | + for (c in (b + 1)..nums.lastIndex) { |
| 24 | + if (nums[a] == prevA && nums[b] == prevB && nums[c] == prevC) { |
| 25 | + continue |
| 26 | + } |
| 27 | + |
| 28 | + val sum3 = nums[a].toLong() + nums[b] + nums[c] |
| 29 | + for (d in (c + 1)..nums.lastIndex) { |
| 30 | + val sum4 = sum3 + nums[d] |
| 31 | + if (sum4 > target) { |
| 32 | + break |
| 33 | + } else if (sum4 == target) { |
| 34 | + result += listOf(nums[a], nums[b], nums[c], nums[d]) |
| 35 | + prevA = nums[a] |
| 36 | + prevB = nums[b] |
| 37 | + prevC = nums[c] |
| 38 | + break |
| 39 | + } |
| 40 | + } |
| 41 | + } |
| 42 | + } |
| 43 | + } |
| 44 | + |
| 45 | + return result |
| 46 | + } |
| 47 | +} |
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