CF718C Sasha and Array 线段树 + 矩阵乘法
有两个操作:
- 将 $[l,r]$所有数 + $x$
- 求 $\sum_{i=l}^{r}fib(i)$
$n=m=10^5$
直接求不好求,改成矩阵乘法的形式:
$a_{i}=M^x\times fib_{1}$
直接用线段树维护 $M^x$ 即可.
因为矩阵乘法是满足结合律的: $A*B+A*C=A*(B+C)$
$a_{i}=M^x\times fib_{1}$
直接用线段树维护 $M^x$ 即可.
因为矩阵乘法是满足结合律的: $A*B+A*C=A*(B+C)$
#include <cstdio> #include <algorithm> #include <cstring> #define lson (now << 1) #define rson (now << 1 | 1) #define ll long long #define setIO(s) freopen(s".in", "r" , stdin) using namespace std; const int N = 200003; const ll mod = 1000000007; struct Matrix { int n, m; ll a[4][4]; ll * operator[] (int x) { return a[x]; } inline void re() { for(int i = 0; i < 3 ; ++i) for(int j = 0; j < 3; ++j) a[i][j] = 0; } inline void I() { re(); for(int i = 0; i < 3 ; ++i) a[i][i] = 1ll; } Matrix friend operator * (Matrix a, Matrix b) { Matrix c; c.re(); int i , j , k; for(i = 0; i < a.n ; ++i) { for(j = 0; j < b.m ; ++j) for(k = 0; k < a.m ; ++k) { c[i][j] = (c[i][j] + (a[i][k] * b[k][j]) % mod) % mod; } } c.n = a.n , c.m = b.m; return c; } Matrix friend operator + (Matrix a, Matrix b) { Matrix c; c.n = 2, c.m = 1; for(int i = 0; i < c.n ; ++i) { for(int j = 0; j < c.m; ++j) c[i][j] = (a[i][j] + b[i][j]) % mod; } return c; } }A[N], M, fib1, v; Matrix operator ^ (Matrix a, int k) { Matrix tmp; tmp.n = tmp.m = 2; for(tmp.I(); k ; a = a * a, k >>= 1) if(k & 1) tmp = tmp * a; return tmp; } inline void init() { M.re(), fib1.re(); M.n = M.m = 2; M[0][0] = 0, M[0][1] = 1, M[1][0] = 1, M[1][1] = 1; fib1.n = 2, fib1.m = 1; fib1[0][0] = 0, fib1[1][0] = 1; } int n , m ; struct Node { Matrix sum, lazy; int tag; }t[N << 2]; inline void pushup(int l, int r, int now) { int mid = (l + r) >> 1; t[now].sum = t[now << 1].sum; if(r > mid) t[now].sum = t[now].sum + t[now << 1 | 1].sum; } inline void mark(int now, Matrix f) { t[now].sum = f * t[now].sum ; t[now].lazy = t[now].lazy * f; t[now].tag = 1; } inline void pushdown(int l, int r, int now) { int mid = (l + r) >> 1; if(t[now].tag) { mark(lson, t[now].lazy); if(r > mid) mark(rson, t[now].lazy); t[now].lazy.I(), t[now].tag = 0; } } void build(int l, int r, int now) { t[now].lazy.n = t[now].lazy.m = 2; t[now].lazy.I(); t[now].tag = 0; if(l == r) { t[now].sum = A[l]; return ; } int mid = (l + r) >> 1; if(mid >= l) build(l, mid, lson); if(r > mid) build(mid + 1, r, rson); pushup(l, r, now); } void update(int l, int r, int now, int L, int R) { if(l >= L && r <= R) { mark(now , v); return ; } pushdown(l, r, now); int mid = (l + r) >> 1; if(L <= mid) update(l, mid, lson, L, R); if(R > mid) update(mid + 1, r, rson, L, R); pushup(l, r, now); } ll query(int l, int r, int now, int L, int R) { if(l >= L && r <= R) return t[now].sum[1][0]; pushdown(l, r, now); int mid = (l + r) >> 1; ll g = 0; if(L <= mid) g += query(l, mid, lson, L, R); if(R > mid) g += query(mid + 1, r, rson, L, R); return (g % mod); } int main() { // setIO("input"); init(); int i , j, x; scanf("%d%d", &n, &m); for(i = 1; i <= n ; ++i) { scanf("%d", &x), A[i] = (M ^ (x - 1)) * fib1; } build(1, n, 1); for(int cas = 1, op , l, r, x; cas <= m ; ++cas) { scanf("%d", &op); if(op == 1) { scanf("%d%d%d", &l, &r, &x); if(x == 0) continue; v = M ^ x; update(1, n, 1, l, r); } if(op == 2) { scanf("%d%d", &l, &r); printf("%lld\n", query(1, n, 1, l, r)); } } return 0; }