From c5aeb890e61d0d39a87915e7aecde6d9e85e7ca4 Mon Sep 17 00:00:00 2001
From: wisdompeak <guan.huifeng@gmail.com>
Date: Sat, 16 Oct 2021 23:39:12 -0700
Subject: [PATCH] Create 2040.Kth-Smallest-Product-of-Two-Sorted-Arrays_v2.cpp

---
 ...allest-Product-of-Two-Sorted-Arrays_v2.cpp | 75 +++++++++++++++++++
 1 file changed, 75 insertions(+)
 create mode 100644 Binary_Search/2040.Kth-Smallest-Product-of-Two-Sorted-Arrays/2040.Kth-Smallest-Product-of-Two-Sorted-Arrays_v2.cpp

diff --git a/Binary_Search/2040.Kth-Smallest-Product-of-Two-Sorted-Arrays/2040.Kth-Smallest-Product-of-Two-Sorted-Arrays_v2.cpp b/Binary_Search/2040.Kth-Smallest-Product-of-Two-Sorted-Arrays/2040.Kth-Smallest-Product-of-Two-Sorted-Arrays_v2.cpp
new file mode 100644
index 000000000..4c8a0186e
--- /dev/null
+++ b/Binary_Search/2040.Kth-Smallest-Product-of-Two-Sorted-Arrays/2040.Kth-Smallest-Product-of-Two-Sorted-Arrays_v2.cpp
@@ -0,0 +1,75 @@
+using LL = long long;
+class Solution {
+public:
+    long long kthSmallestProduct(vector<int>& nums1, vector<int>& nums2, long long k) 
+    {
+        if (nums1.size() > nums2.size())
+            return kthSmallestProduct(nums2, nums1, k);
+                
+        LL left = -1e10, right = 1e10;
+        while (left < right)
+        {
+            LL mid = left+(right-left)/2;
+            LL count = countSmallerOrEqual(mid, nums1, nums2);
+            if (count < k)
+                left = mid+1;
+            else
+                right = mid;                
+        }
+        return left;
+    }
+    
+    LL countSmallerOrEqual(LL mid, vector<int>& nums1, vector<int>& nums2)
+    {
+        LL ret = 0;
+        
+        if (mid >= 0)
+        {
+            int j0 = nums2.size()-1;
+            int j1 = nums2.size()-1;
+            
+            for (int i=0; i<nums1.size(); i++)
+            {
+                if (nums1[i]>0)
+                {
+                    while (j0>=0 && (LL)nums1[i]*(LL)nums2[j0] > mid)
+                        j0--;
+                    ret += j0+1;
+                }
+                else if (nums1[i]==0)
+                    ret += nums2.size();
+                else
+                {
+                    while (j1>=0 && (LL)nums1[i]*(LL)nums2[j1] <= mid)
+                        j1--;
+                    ret += nums2.size()-1-j1;
+                }
+            }
+        }
+        else
+        {
+            int j0 = 0;
+            int j1 = 0;
+            
+            for (int i=0; i<nums1.size(); i++)
+            {
+                if (nums1[i]>0)
+                {
+                    while (j0<nums2.size() && (LL)nums1[i]*(LL)nums2[j0] <= mid)
+                        j0++;
+                    ret += j0;
+                }
+                else if (nums1[i]==0)
+                    ret += 0;
+                else
+                {
+                    while (j1<nums2.size() && (LL)nums1[i]*(LL)nums2[j1] > mid)
+                        j1++;
+                    ret += nums2.size()-j1;
+                }
+            }
+        }
+        
+        return ret;
+    }
+};