using min heap to find k smallest pairs from two arrays

Author: Arjiit

Two Pointers/kSmallestPairs.java

@@ -0,0 +1,29 @@
+class Solution {
+// O(KlogK) solution
+/*
+    Putting all the elements combination from one array element to other and then
+    traversing in second array to find other smallest pairs.
+*/
+    public List<List<Integer>> kSmallestPairs(int[] nums1, int[] nums2, int k) {
+        List<List<Integer>> finalRes = new ArrayList<>();
+        if(nums1.length==0 || nums2.length==0 || k==0) return finalRes;
+        int len1 = nums1.length;
+        int len2 = nums2.length;
+        PriorityQueue<int[]> pq = new PriorityQueue<>((a,b) -> (a[0] + a[1]) - (b[0]+ b[1]));
+        for (int i=0; i<len1&& i<k; i++){
+            pq.offer(new int[]{nums1[i], nums2[0], 0}); //storing index of nums2 traversal
+        }
+        while(k-- > 0 && !pq.isEmpty()) {
+            int[] cur = pq.poll();
+            List<Integer> res = new ArrayList<>();
+            res.add(cur[0]);
+            res.add(cur[1]);
+            finalRes.add(res);
+            int num2index = cur[2];
+            if(num2index + 1 < nums2.length){
+                pq.offer(new int[]{cur[0],nums2[num2index+1], num2index+1});
+            }
+        }
+        return finalRes;
+    }
+}