- Add: Kth Smallest Element in a Sorted Matrix

Author: BNSC1

LeetCode/378. Kth Smallest Element in a Sorted Matrix.kt

@@ -0,0 +1,20 @@
+class Solution {
+    fun kthSmallest(m: Array<IntArray>, kth: Int): Int {
+        val size = m.size
+        val pq = PriorityQueue<Pair<Int, Int>>( compareBy { m[it.first][it.second] } ) //coordinates in min heap
+
+        repeat(size) { row -> //add first element of each row
+            pq.offer(row to 0)
+        }
+        
+        var nth = 0    
+        while (true) {
+            nth++
+            val poll = pq.poll()
+            if (nth == kth) return m[poll.first][poll.second]
+            if (poll.second + 1 < size) { //offer the next element of the row if avails
+                pq.offer(poll.first to poll.second+1)
+            }
+        }
+    }
+}