solved D2 Q2

Author: arnavsingh010

Problems/Mathematics/Day-02/sol/Arnav_Singh/.cph/.Solution1.cpp_8a03896c340660fc53d23e6afdd07dd2.prob

@@ -0,0 +1 @@
+{"name":"Local: Solution2","url":"\\\\wsl.localhost\\Ubuntu\\home\\arnav\\cp\\CP-Chronicles\\Problems\\Mathematics\\Day-02\\sol\\Arnav_Singh\\Solution2.cpp","tests":[{"id":1766903282354,"input":"","output":""}],"interactive":false,"memoryLimit":1024,"timeLimit":3000,"srcPath":"\\\\wsl.localhost\\Ubuntu\\home\\arnav\\cp\\CP-Chronicles\\Problems\\Mathematics\\Day-02\\sol\\Arnav_Singh\\Solution2.cpp","group":"local","local":true}

Problems/Mathematics/Day-02/sol/Arnav_Singh/.cph/.Solution2.cpp_2ff86a5bba8a0489efed8cfae804bdee.prob

@@ -0,0 +1,60 @@
+#include <bits/stdc++.h>
+using namespace std;
+
+long long fact[1005];
+const long long MOD = 1e9 + 7;
+void init() {
+    fact[0] = 1;
+    for (int i = 1; i <= 1000; i++)
+        fact[i] = fact[i - 1] * i % MOD;
+}
+long long modpow(long long a, long long b) {
+    long long res = 1;
+    while (b) {
+        if (b & 1) res = res * a % MOD;
+        a = a * a % MOD;
+        b >>= 1;
+    }
+    return res;
+}
+
+int main() {
+    init();
+     int t;
+    cin >> t;
+    while(t--) {
+        int n,k;
+        cin>>n>>k;
+        long long a[n];
+        for (int i = 0; i < n; ++i) {
+            cin>>a[i];
+        }
+        sort(a,a+n);
+        reverse(a,a+n);
+        long long repeat =a[k-1];
+        int avl=0;
+        unordered_map<long long,long long> m;
+        for (int i = 0; i < k; ++i) {
+            m[a[i]]++;
+        }
+        for (int i = 0; i < n; ++i) {
+            if(a[i]==repeat){
+                avl++;
+            }
+        }
+        int ans=1;
+        for(auto &[key,val]:m){
+            if(key==repeat){
+            ans = fact[avl] * modpow(fact[avl - val], MOD - 2) % MOD * modpow(fact[val], MOD - 2) % MOD;
+            }
+            else{
+                ans*=1;
+            }
+        }
+        cout << ans <<'\n';
+    }
+    
+    return 0;
+}
+//time complexity - O(nlogn)
+//https://codeforces.com/contest/1475/submission/355454659