Create 2018-H-C.cpp

Author: tmp-coder

Diff for: kick-start/2018-H-C.cpp

@@ -0,0 +1,79 @@
+#include<bits/stdc++.h>
+
+using namespace std;
+
+#define ms(x,v) memset(x,(v), sizeof(x))
+#define msn(x,v,n) memset(x,(v),sizeof(x[0]) * n)
+#define INF 0x3f3f3f3f
+#define random(a,b) (rand() % ((b) -(a)) +(a))
+
+typedef long long LL;
+typedef pair<int,int> PII;
+
+const double EPS = 2e-8;
+const LL MOD = 1e9+7;
+const int MAX_FAC = 1e5+10;
+LL fac[MAX_FAC * 2];
+
+void init(){
+    fac[0] =1;
+    for(int i=1 ; i < MAX_FAC * 2 ; ++i)
+        fac[i] = fac[i-1] * i % MOD;
+}
+
+LL power_mod(LL x,LL n,LL mod){
+    LL ret = 1;
+    while (n)
+    {
+        if(n&1) ret = x * ret % mod;
+        x = x * x % mod;
+        n >>= 1;
+    }
+    return ret;
+}
+
+void solve(){
+    int N,M;
+    cin >> N >> M;
+
+    LL ans =0;
+    LL power2 = 1;
+    for(int k=0;  k<=M; ++k){
+
+        LL cur_ans = power2;
+        power2 = power2 *2 % MOD;
+        cur_ans = cur_ans * fac[M] % MOD * fac[2*N - k] % MOD;
+        cur_ans = cur_ans * power_mod(fac[k] * fac[M-k]% MOD,MOD -2 ,MOD) % MOD;
+
+        ans += k&1 ? MOD - cur_ans : cur_ans;
+        ans %= MOD;
+    }
+
+    cout << " "<<ans;
+}
+
+int main(int argc, char const *argv[])
+{   
+    
+    ios :: sync_with_stdio(0);
+    cin.tie(0);
+    // cout.tie(0);
+    std::cout.precision(8);
+    std::cout.setf( std::ios::fixed, std:: ios::floatfield );
+
+    init();
+
+
+    int T;
+    cin >> T;
+    
+    for(int kase =1;  kase <= T ; ++kase)
+    {   
+        cout << "Case #"<<kase << ":";
+
+        solve();
+        cout << '\n';
+    }
+
+    return 0;
+}