bzoj 5337 [TJOI2018] str

bzoj 5337 [TJOI2018] str

Link

Solution

水题

直接 (f[i][j]) 表示以第 (i) 位为结束位置，当前已经匹配了前 (j) 个氨基酸的方案数

使用哈希转移

转移复杂度 (O(10))，总复杂度 (1e7)

Code

#include<stdio.h>
#include<cstring>
#include<cstdlib>
#include<algorithm>
#include<vector>
#include<map>
#include<set>
#include<cmath>
#include<iostream>
#include<queue>
#include<string>
#include<ctime>
using namespace std;
typedef long long ll;
typedef pair<int,int> pii;
typedef long double ld;
typedef unsigned long long ull;
typedef pair<long long,long long> pll;
#define fi first
#define se second
#define pb push_back
#define mp make_pair
#define rep(i,j,k)  for(register int i=(int)(j);i<=(int)(k);i++)
#define rrep(i,j,k) for(register int i=(int)(j);i>=(int)(k);i--)
#define Debug(...) fprintf(stderr, __VA_ARGS__)

ll read(){
	ll x=0,f=1;char c=getchar();
	while(c<'0' || c>'9'){if(c=='-')f=-1;c=getchar();}
	while(c>='0' && c<='9'){x=x*10+c-'0';c=getchar();}
	return x*f;
}

const int md = 1e9 + 7;
const ll mod = 2002070919ll;
const int maxn = 10010;
int n, len;
char s[maxn], t[maxn];
int l[110][12], a[110], f[maxn][110];
ll hsh[110][12], pw[maxn], h[maxn];

inline void add(int &x, int y) {
	x += y;
	if (x >= md) x -= md;
}
inline ll calc(int l, int r) {
	return (h[r] - h[l - 1] * pw[r - l + 1] % mod + mod) % mod;
}
void work(){
	n = read();
	scanf("%s", s + 1);
	len = strlen(s + 1);
	pw[0] = 1; rep(i, 1, len) pw[i] = pw[i - 1] * 100 % mod;
	rep(i, 1, len) h[i] = (h[i - 1] * 100 + s[i] - 'A') % mod;
	rep(i, 1, n) {
		a[i] = read();
		rep(j, 1, a[i]) {
			scanf("%s", t + 1);
			l[i][j] = strlen(t + 1);
			rep(k, 1, l[i][j]) hsh[i][j] = (hsh[i][j] * 100 + t[k] - 'A') % mod;
		}
	}
	rep(i, 0, len) f[i][0] = 1;
	rep(i, 1, len) rep(j, 1, n) {
		rep(k, 1, a[j]) {
			int nw = l[j][k];
			if (i < nw || !f[i - nw][j - 1]) continue;
			ll val = calc(i - nw + 1, i);
			if (val == hsh[j][k]) add(f[i][j], f[i - nw][j - 1]);
		}
	}
	int ans = 0;
	rep(i, 1, len) add(ans, f[i][n]);
	printf("%d
", ans);
}

int main(){
	#ifdef LZT
		freopen("in","r",stdin);
	#endif
	
	work();
	
	#ifdef LZT
		Debug("My Time: %.3lfms
", (double)clock() / CLOCKS_PER_SEC);
	#endif
}

Review

注意哈希的模数不能大过 (INT\_MAX)，不然两个哈希值相乘会爆 ( ext{long long})