luogu1368 工艺

题目链接

思路

\(SAM\)练手题，将原串重复一遍插入到\(SAM\)中，然后贪心走长度为n的一个路径即可。

不用担心会直接走到终点，根据\(SAM\)的构造方式可以发现会先走到前面的路径。

代码

/*
* @Author: wxyww
* @Date:   2019-07-11 11:09:25
* @Last Modified time: 2019-07-11 11:20:42
*/
#include<cstdio>
#include<map>
#include<iostream>
#include<cstdlib>
#include<cstring>
#include<algorithm>
#include<queue>
#include<vector>
#include<ctime>
using namespace std;
typedef long long ll;
const int N = 600000 + 100;
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;
}
struct node {
	int len,fa;
	map<int,int>ch;
}SAM[N << 1];
int lst = 1,tot = 1;
void add(int c) {
	int cur = ++tot,p = lst;
	SAM[cur].len = SAM[p].len + 1;
	while(p && !SAM[p].ch[c]) {
		SAM[p].ch[c] = cur;
		p = SAM[p].fa;
	}
	if(!p) SAM[cur].fa = 1;
	else {
		int q = SAM[p].ch[c];
		if(SAM[q].len == SAM[p].len + 1) SAM[cur].fa = q;
		else {
			int clone = ++tot;
			SAM[clone] = SAM[q];
			SAM[clone].len = SAM[p].len + 1;
			while(p && SAM[p].ch[c] == q) {
				SAM[p].ch[c] = clone;
				p = SAM[p].fa;
			}
			SAM[q].fa = SAM[cur].fa = clone;
		}
	}
	lst = cur;
}
int a[N];
int main() {
	int n = read();
	for(int i = 1;i <= n;++i) a[i] = read();
	for(int i = 1;i <= n;++i) add(a[i]);
	for(int i = 1;i <= n;++i) add(a[i]);
	int p = 1;
	for(int i = 1;i <= n;++i) {
		printf("%d ",SAM[p].ch.begin() -> first);
		p = SAM[p].ch.begin() -> second;
	}
	return 0;
}