Time: 66 ms (54.76%), Space: 60.3 MB (80.83%) - LeetHub

Author: MishkatIT

2699-count-the-number-of-fair-pairs/2699-count-the-number-of-fair-pairs.cpp

@@ -0,0 +1,14 @@
+class Solution {
+public:
+    long long countFairPairs(vector<int>& nums, int lower, int upper) {
+        sort(nums.begin(), nums.end());
+        int n = nums.size();
+        long long ans = 0;
+        for (int i = 1; i < n; i++) {
+            int ub = upper_bound(nums.begin() + i, nums.end(), upper - nums[i - 1]) - nums.begin() + i;
+            int lb = lower_bound(nums.begin() + i, nums.end(), lower - nums[i - 1]) - nums.begin() + i;
+            ans += ub - lb;
+        }
+        return ans;
+    }
+};