From 36c1ad8ffa16345096c19c08ed8879ebb645e625 Mon Sep 17 00:00:00 2001
From: Sudo-Aditi <96663557+Sudo-Aditi@users.noreply.github.com>
Date: Wed, 4 Oct 2023 18:24:41 +0530
Subject: [PATCH] Create Count the number of fair prices

---
 Count the number of fair prices | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)
 create mode 100644 Count the number of fair prices

diff --git a/Count the number of fair prices b/Count the number of fair prices
new file mode 100644
index 00000000..880b1d18
--- /dev/null
+++ b/Count the number of fair prices	
@@ -0,0 +1,18 @@
+A  VERY NICE implementation of BINARY SEARCH TO BE LEARNT HERE
+
+class Solution {
+public:
+    long long countFairPairs(vector<int>& nums, int lower, int upper) {
+        long long int ans = 0;
+        sort(nums.begin(),nums.end());
+        for(int i=0;i<nums.size()-1;i++){
+            long long int l = lower-nums[i];
+            long long int h = upper-nums[i];
+            long long int l_b = lower_bound(nums.begin()+i+1,nums.end(),l)-nums.begin();
+            long long int u_b = upper_bound(nums.begin()+i+1,nums.end(),h)-nums.begin();
+
+            ans += (u_b - l_b);
+        }
+        return ans;
+    }
+};