Day 2 Solution 1

Author: Apoorv012

Problems/Mathematics/Day-02/sol/Apoorv012/Solution1.cpp

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+/*
+
+Count the number of interesting pairs (ai,aj) that have the max. absolute difference.
+
+Ans = count(min el) * count(max el)
+
+Time: O(n)
+Space: O(1)
+
+Submission Link: https://codeforces.com/contest/1771/submission/355675072
+
+*/
+
+#include <bits/stdc++.h>
+using namespace std;
+
+using ll = long long;
+
+int main() {
+    ll t;
+    cin >> t;
+    while (t--) {
+        ll n;
+        cin >> n;
+        unordered_map<ll, ll> mp;
+        ll _max = LONG_LONG_MIN, _min = LONG_LONG_MAX;
+        for (ll i = 0; i < n; i++) {
+            ll el;
+            cin >> el;
+            mp[el]++;
+            _max = max(_max, el);
+            _min = min(_min, el);
+        }
+        ll ans;
+        if (_max == _min) {
+            ans = n * (n-1);
+        }
+        else {
+            ans = 2 * mp[_min] * mp[_max];
+        }
+        cout << ans << endl;
+    }
+}