LeetCode in Kotlin
2007. Find Original Array From Doubled Array
Medium
An integer array original is transformed into a doubled array changed by appending twice the value of every element in original, and then randomly shuffling the resulting array.
Given an array changed, return original if changed is a doubled array. If changed is not a doubled array, return an empty array. The elements in original may be returned in any order.
Example 1:
Input: changed = [1,3,4,2,6,8]
Output: [1,3,4]
Explanation: One possible original array could be [1,3,4]:
-
Twice the value of 1 is 1 * 2 = 2.
-
Twice the value of 3 is 3 * 2 = 6.
-
Twice the value of 4 is 4 * 2 = 8.
Other original arrays could be [4,3,1] or [3,1,4].
Example 2:
Input: changed = [6,3,0,1]
Output: []
Explanation: changed is not a doubled array.
Example 3:
Input: changed = [1]
Output: []
Explanation: changed is not a doubled array.
Constraints:
1 <= changed.length <= 1050 <= changed[i] <= 105
Solution
class Solution {
fun findOriginalArray(changed: IntArray): IntArray {
if (changed.size % 2 == 1) {
return IntArray(0)
}
val a = IntArray(100001)
for (j in changed) {
a[j]++
}
if (a[0] % 2 == 1) {
return IntArray(0)
}
val ans = IntArray(changed.size / 2)
var p = 0
if (a[0] > 0) {
a[0] /= 2
while (a[0] > 0) {
ans[p++] = 0
a[0]--
}
}
for (i in 1..100001 / 2) {
if (a[i] == 0) {
continue
}
val tmp = i * 2
if (a[tmp] >= a[i]) {
a[tmp] = a[tmp] - a[i]
while (a[i] > 0) {
ans[p++] = i
a[i]--
}
} else {
return IntArray(0)
}
}
for (i in 1 until a.size) {
if (a[i] != 0) {
return IntArray(0)
}
}
return ans
}
}