题目描述
Bessie is playing a video game! In the game, the three letters ‘A‘, ‘B‘, and ‘C‘ are the only valid buttons. Bessie may press the buttons in any order she likes; however, there are only N distinct combos possible (1 <= N <= 20). Combo i is represented as a string S_i which has a length between 1 and 15 and contains only the letters ‘A‘, ‘B‘, and ‘C‘.
Whenever Bessie presses a combination of letters that matches with a combo, she gets one point for the combo. Combos may overlap with each other or even finish at the same time! For example if N = 3 and the three possible combos are "ABA", "CB", and "ABACB", and Bessie presses "ABACB", she will end with 3 points. Bessie may score points for a single combo more than once.
Bessie of course wants to earn points as quickly as possible. If she presses exactly K buttons (1 <= K <= 1,000), what is the maximum number of points she can earn?
贝西在玩一款游戏,该游戏只有三个技能键 “A”“B”“C”可用,但这些键可用形成N种(1 <= N<= 20)特定的组合技。第i个组合技用一个长度为1到15的字符串S_i表示。
当贝西输入的一个字符序列和一个组合技匹配的时候,他将获得1分。特殊的,他输入的一个字符序列有可能同时和若干个组合技匹配,比如N=3时,3种组合技分别为"ABA", "CB", 和"ABACB",若贝西输入"ABACB",他将获得3分。
若贝西输入恰好K (1 <= K <= 1,000)个字符,他最多能获得多少分?
输入输出格式
输入格式:
- Line 1: Two space-separated integers: N and K.
- Lines 2..N+1: Line i+1 contains only the string S_i, representing combo i.
输出格式:
- Line 1: A single integer, the maximum number of points Bessie can obtain.
输入输出样例
输入样例#1:
3 7
ABA
CB
ABACB
输出样例#1:
4
说明
The optimal sequence of buttons in this case is ABACBCB, which gives 4 points--1 from ABA, 1 from ABACB, and 2 from CB.
最简单的AC自动机+DP了。。。。再不会的话AC自动机白学了。
#include<bits/stdc++.h> #define ll long long #define maxn 1005 using namespace std; int ch[maxn][3],n,m,k,ans=0; int root=0,tot=0,val[maxn]; int f[maxn],g[maxn][maxn]; char s[maxn]; inline int id(char c){ return c-‘A‘; } inline void ins(){ int len=strlen(s),now=root; for(int i=0;i<len;i++){ int c=id(s[i]); if(!ch[now][c]) ch[now][c]=++tot; now=ch[now][c]; } val[now]=1; } inline void get_fail(){ queue<int> q; for(int i=0;i<3;i++) if(ch[0][i]){ q.push(ch[0][i]); } int r,v,x; while(!q.empty()){ x=q.front(),q.pop(); for(int i=0;i<3;i++){ r=ch[x][i]; if(!r){ ch[x][i]=ch[f[x]][i]; continue; } q.push(r); f[r]=ch[f[x]][i]; val[r]+=val[f[r]]; } } } inline void dp(){ memset(g,-0x3f,sizeof(g)); g[0][0]=0; int to; for(int i=0;i<k;i++) for(int j=0;j<=tot;j++) for(int u=0;u<3;u++){ to=ch[j][u]; g[i+1][to]=max(g[i+1][to],g[i][j]+val[to]); } for(int i=0;i<=tot;i++) ans=max(ans,g[k][i]); } int main(){ scanf("%d%d",&n,&k); for(int i=1;i<=n;i++){ scanf("%s",s); ins(); } get_fail(); dp(); printf("%d\n",ans); return 0; }
原文地址:https://www.cnblogs.com/JYYHH/p/8280569.html