update ucpc2026

source/Math/NTT.cpp

@@ -1,32 +1,26 @@
 namespace GMS {
 template<ll mod>
 ll pow(ll a, ll b) {
-    a %= mod;
-    ll ret = 1;
+    ll ret = 1; a %= mod;
     while(b != 0) {
         if(b&1) ret = ret*a%mod;
-        a = a*a%mod; b>>=1;
+        a = a*a%mod, b/=2;
     }
     return ret;
 }
 template<ll mod, ll w>
-void ntt(vector<ll> &a, bool inv = false) {
+void ntt(vl& a, bool inv = false) {
     static_assert(mod <= (ll)2e9, "mod should be less than 2e9");
     int n = a.size(), j = 0;
-    
     assert((n & -n) == n && (mod-1)%n == 0);
 
     for(int i=1; i<n; i++) {
-        int bit = (n >> 1);
-        while(j >= bit) {
-            j -= bit;
-            bit >>= 1;
-        }
-        j += bit;
-        if(i < j) swap(a[i], a[j]);
+        int bit = n/2;
+        while(j >= bit) {j -= bit; bit >>= 1;}
+        j += bit; if(i < j) swap(a[i], a[j]);
     }
     
-    static vector<ll> root[30], iroot[30];
+    static vl root[30], iroot[30];
     for(int st=1; (1<<st) <= n; st++) {
         if(root[st].empty()) {
             ll t = pow<mod>(w, (mod-1)/(1<<st));
@@ -46,7 +40,6 @@ void ntt(vector<ll> &a, bool inv = false) {
     }
     
     vector<ll>* r = (inv?root:iroot);
-    
     for(int st = 1; (1<<st) <= n; st++) {
         int i = 1<<st; //int step = n / i;
         for(int j=0; j<n; j+=i) {
@@ -70,12 +63,9 @@ vl conv(vl A, vl B) {
     A.resize(t); B.resize(t);
 
     ntt<mod, w>(A); ntt<mod, w>(B);
-
     fors(i, 0, t-1) A[i] = A[i]*B[i]%mod;
-    
     ntt<mod, w>(A, true);
-    A.resize(n+m-1);
     
-    return A;
+    return A.resize(n+m-1), A;
 }
 } // namespace GMS