bzoj 4002: [JLOI2015]有意义的字符串

Posted 2020-06-13

　　这个题。。。

　　

 1 #include <bits/stdc++.h>
 2 #define rep(i, a, b) for (int i = a; i <= b; i++)
 3 #define drep(i, a, b) for (int i = a; i >= b; i--)
 4 #define REP(i, a, b) for (int i = a; i < b; i++)
 5 #define mp make_pair
 6 #define pb push_back
 7 #define clr(x) memset(x, 0, sizeof(x))
 8 #define xx first #define yy second
 9 using namespace std;
10 typedef pair<int, int> pii;
11 typedef unsigned long long ll;
12 const int inf = 0x3f3f3f3f;
13 const ll INF = 0x3f3f3f3f3f3f3f3fll;
14 //************************************************
15  
16 const ll mod = 7528443412579576937LL;
17 ll mul(ll base, ll num) {
18     ll ret(0);
19     while (num) {
20         if (num & 1) ret = (ret + base) % mod;
21         base = (base + base) % mod;
22         num >>= 1;
23     }
24     return ret;
25 }
26 struct matrix {
27     ll s[3][3]; matrix () { clr(s); }
28     matrix operator * (const matrix &B) const {
29         matrix A = *this, C;
30         rep(i, 1, 2) rep(j, 1, 2) rep(k, 1, 2)
31             C.s[i][j] = (C.s[i][j] + mul(A.s[i][k], B.s[k][j]) % mod) % mod;
32         return C;
33     }
34 } ori;
35  
36 matrix POW(matrix base, ll num) {
37     matrix ret = ori;
38     while (num) {
39         if (num & 1) ret = ret * base;
40         base = base * base;
41         num >>= 1;
42     }
43     return ret;
44 }
45  
46 int main() {
47     ll b, d, n; scanf("%llu%llu%llu", &b, &d, &n);
48     ll a = b, c = (d - b * b) >> 2;
49     ori.s[1][1] = ori.s[2][2] = 1;
50     matrix base; base.s[1][1] = a, base.s[2][1] = c, base.s[1][2] = 1;
51     matrix ans;
52     ans.s[1][2] = 2, ans.s[1][1] = b;
53     ans = ans * POW(base, n);
54     if (d != b * b && n % 2 == 0) ans.s[1][2]--;
55     printf("%llu\n", ans.s[1][2]);
56 }

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