Create 0645-set-mismatch.kt

Author: a93a

kotlin/0645-set-mismatch.kt

@@ -0,0 +1,81 @@
+// O(n) time and O(1) space
+class Solution {
+    fun findErrorNums(nums: IntArray): IntArray {
+        val n = nums.size
+
+        var x = 0
+        var y = 0
+        for (i in 1..n) {
+            x += nums[i - 1] - i
+            y += nums[i - 1] * nums[i - 1] - i * i
+        }
+
+        var missing = (y - x * x) / (2 * x)
+        var duplicate = missing + x
+
+        return intArrayOf(duplicate, missing)
+    }
+}
+
+// Inplace data manipulation O(n) time and O(1) space
+class Solution {
+    fun findErrorNums(nums: IntArray): IntArray {
+        val res = IntArray (2)
+
+        for (i in nums.indices) {
+            val n = Math.abs(nums[i])
+            nums[n - 1] = -1 * nums[n - 1]
+            if (nums[n - 1] > 0)
+                res[0] = n
+        }
+
+        for ((i, n) in nums.withIndex()) {
+            if (n > 0 && i + 1 != res[0]) {
+                res[1] = i + 1
+                break
+            }
+        }
+        
+        return res
+    }
+}
+
+// HashMap O(n) time and O(n) space
+class Solution {
+    fun findErrorNums(nums: IntArray): IntArray {
+        val res = IntArray (2)
+        val counts = nums
+            .asList()
+            .groupingBy { it }
+            .eachCount()
+
+        for (num in 1..nums.size) {
+            val count = counts[num] ?: 0
+            if (count == 0)
+                res[1] = num
+            if (count == 2)
+                res[0] = num
+        }
+
+        return res
+    }
+}
+
+// Use XOR O(n) time and O(1) space
+class Solution {
+    fun findErrorNums(nums: IntArray): IntArray {
+        val res = IntArray (2)
+
+        for (i in nums.indices) {
+            val num = Math.abs(nums[i])
+
+            res[1] = res[1] xor ((i + 1) xor num)
+
+            if (nums[num - 1] < 0) res[0] = num
+            else nums[num - 1] *= -1
+        }
+        
+        res[1] = res[1] xor res[0]
+        return res
+    }
+}