g0001_0100.s0018_4sum.Solution.kt Maven / Gradle / Ivy
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Kotlin-based LeetCode algorithm problem solutions, regularly updated
package g0001_0100.s0018_4sum
// #Medium #Array #Sorting #Two_Pointers #2023_07_03_Time_229_ms_(98.59%)_Space_37.8_MB_(100.00%)
class Solution {
fun fourSum(nums: IntArray, target: Int): List> {
val n = nums.size
nums.sort()
val result: MutableList> = ArrayList()
for (i in 0 until n - 3) {
if (i > 0 && nums[i] == nums[i - 1]) {
continue
}
if (nums[i].toLong() + nums[i + 1] + nums[i + 2] + nums[i + 3] > target) {
break
}
if (nums[i].toLong() + nums[n - 3] + nums[n - 2] + nums[n - 1] < target) {
continue
}
for (j in i + 1 until n - 2) {
if (j > i + 1 && nums[j] == nums[j - 1]) {
continue
}
if (nums[j].toLong() + nums[j + 1] + nums[j + 2] > target - nums[i]) {
break
}
if (nums[j].toLong() + nums[n - 2] + nums[n - 1] < target - nums[i]) {
continue
}
val tempTarget = target - (nums[i] + nums[j])
var low = j + 1
var high = n - 1
while (low < high) {
val curSum = nums[low] + nums[high]
if (curSum == tempTarget) {
val tempList: MutableList = ArrayList()
tempList.add(nums[i])
tempList.add(nums[j])
tempList.add(nums[low])
tempList.add(nums[high])
result.add(tempList)
low++
high--
while (low < high && nums[low] == nums[low - 1]) {
low++
}
while (low < high && nums[high] == nums[high + 1]) {
high--
}
} else if (curSum < tempTarget) {
low++
} else {
high--
}
}
}
}
return result
}
}