lightoj 1427 Substring Frequency (||) (AC自动机)
1427 - Substring Frequency (II)
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| Time Limit: 5 second(s) | Memory Limit: 128 MB |
A string is a finite sequence of symbols that are chosen from an alphabet. In this problem you are given a string T and n queries each with a string Pi, where the strings contain lower case English alphabets only. You have to find the number of times Pi occurs as a substring of T.
Input
Input starts with an integer T (≤ 10), denoting the number of test cases.
Each case starts with a line containing an integer n (1 ≤ n ≤ 500). The next line contains the string T (1 ≤ |T| ≤ 106). Each of the next n lines contains a string Pi(1 ≤ |Pi| ≤ 500).
Output
For each case, print the case number in a single line first. Then for each string Pi, report the number of times it occurs as a substring of T in a single line.
Sample Input |
Output for Sample Input |
| 2 5 ababacbabc aba ba ac a abc 3 lightoj oj light lit |
Case 1: 2 3 1 4 1 Case 2: 1 1 0 |
Notes
1. Dataset is huge, use faster I/O methods.
2. If S is a string then |S| denotes the length of S.
题目链接：http://lightoj.com/volume_showproblem.php?problem=1427
题目大意：问单词在给定的段落中出现的次数
题目分析：AC自动机，注意单词可能重复，插单词的时候标记一下，把idx转到其第一次出现的坐标，本题动态new的话，不delete会mle，delete会超时
下面给出三种常见姿势和一个神奇姿势:
1.普通静态指针型 (3956 ms)
#include <cstdio>
#include <cstring>
int const MAXN = 1e6 + 5;
int const MAXM = 505;
char s[MAXM], t[MAXN];
int tail, head, sz;
int ans[MAXM], cg[MAXM];
struct NODE
{
int cnt;
int id;
int idx;
NODE *fail;
NODE *next[26];
}*q[MAXM * MAXM], *root, *f, node[MAXM * MAXM];
inline void Newnode(NODE * &x)
{
x = &node[sz];
x -> id = sz ++;
x -> cnt = 0;
x -> idx = 0;
x -> fail = NULL;
memset(x -> next, NULL, sizeof(x -> next));
}
inline void Init()
{
sz = 0;
head = tail = 0;
f = &node[0];
f -> id = 0;
f -> cnt = 0;
f -> idx = 0;
f -> fail = NULL;
memset(f -> next, NULL, sizeof(f -> next));
Newnode(root);
}
inline void Insert(NODE *p, char *s, int id)
{
int len = strlen(s);
for(int i = 0; i < len; i++)
{
int idx = s[i] - 'a';
if(p -> next[idx] == NULL)
Newnode(p -> next[idx]);
p = p -> next[idx];
}
if(p -> cnt)
cg[id] = p -> id;
else
{
p -> id = id;
p -> cnt = 1;
}
}
inline void Build_AC(NODE *root)
{
q[tail ++] = root;
while(tail != head)
{
NODE *p = q[head ++];
for(int i = 0; i < 26; i++)
{
if(p -> next[i] != NULL)
{
if(p == root)
p -> next[i] -> fail = root;
else
{
NODE *tmp = p -> fail;
while(tmp != NULL)
{
if(tmp -> next[i] != NULL)
{
p -> next[i] -> fail = tmp -> next[i];
break;
}
tmp = tmp -> fail;
}
if(tmp == NULL)
p -> next[i] -> fail = root;
}
q[tail ++] = p -> next[i];
}
}
}
}
inline void Query(NODE *root, char *t)
{
NODE *p = root;
int len = strlen(t);
for(int i = 0; i < len; i++)
{
int idx = t[i] - 'a';
while(p != root && p -> next[idx] == NULL)
p = p -> fail;
if(p -> next[idx] == NULL)
p = root;
else
p = p -> next[idx];
NODE *tmp = p;
while(tmp != root)
{
ans[tmp -> id] += tmp -> cnt;
tmp = tmp -> fail;
}
}
}
int main()
{
int T;
scanf("%d", &T);
for(int ca = 1; ca <= T; ca++)
{
memset(ans, 0, sizeof(ans));
memset(cg, -1, sizeof(cg));
Init();
int n;
scanf("%d", &n);
scanf("%s", t);
for(int i = 0; i < n; i++)
{
scanf("%s", s);
Insert(root, s, i);
}
Build_AC(root);
Query(root, t);
printf("Case %d:\n", ca);
for(int i = 0; i < n; i++)
{
if(cg[i] != -1)
printf("%d\n", ans[cg[i]]);
else
printf("%d\n", ans[i]);
}
}
}
2.Tire图优化静态指针型 (4000ms) 。。反而更慢
#include <cstdio>
#include <cstring>
int const MAXN = 1e6 + 5;
int const MAXM = 505;
char s[MAXM], t[MAXN];
int tail, head, sz;
int ans[MAXM], cg[MAXM];
struct NODE
{
int cnt;
int id;
int idx;
NODE *fail;
NODE *next[26];
}*q[MAXM * MAXM], *root, *f, node[MAXM * MAXM];
inline void Newnode(NODE * &x)
{
x = &node[sz];
x -> id = sz ++;
x -> cnt = 0;
x -> idx = 0;
x -> fail = NULL;
memset(x -> next, NULL, sizeof(x -> next));
}
inline void Init()
{
sz = 0;
head = tail = 0;
f = &node[0];
f -> id = 0;
f -> cnt = 0;
f -> idx = 0;
f -> fail = NULL;
memset(f -> next, NULL, sizeof(f -> next));
Newnode(root);
}
inline void Insert(NODE *p, char *s, int id)
{
int len = strlen(s);
for(int i = 0; i < len; i++)
{
int idx = s[i] - 'a';
if(p -> next[idx] == NULL)
Newnode(p -> next[idx]);
p = p -> next[idx];
}
if(p -> cnt)
cg[id] = p -> id;
else
{
p -> id = id;
p -> cnt = 1;
}
}
inline void Build_AC(NODE *root)
{
q[tail ++] = root;
while(tail != head)
{
NODE *p = q[head ++];
for(int i = 0; i < 26; i++)
{
if(p -> next[i] != NULL)
{
if(p == root)
p -> next[i] -> fail = root;
else
p -> next[i] -> fail = p -> fail -> next[i];
q[tail ++] = p -> next[i];
}
else
{
if(p == root)
p -> next[i] = root;
else
p -> next[i] = p -> fail -> next[i];
}
}
}
}
inline void Query(NODE *root, char *t)
{
NODE *p = root;
int len = strlen(t);
for(int i = 0; i < len; i++)
{
int idx = t[i] - 'a';
while(p != root && p -> next[idx] == NULL)
p = p -> fail;
if(p -> next[idx] == NULL)
p = root;
else
p = p -> next[idx];
NODE *tmp = p;
while(tmp != root)
{
ans[tmp -> id] += tmp -> cnt;
tmp = tmp -> fail;
}
}
}
int main()
{
int T;
scanf("%d", &T);
for(int ca = 1; ca <= T; ca++)
{
memset(ans, 0, sizeof(ans));
memset(cg, -1, sizeof(cg));
Init();
int n;
scanf("%d", &n);
scanf("%s", t);
for(int i = 0; i < n; i++)
{
scanf("%s", s);
Insert(root, s, i);
}
Build_AC(root);
Query(root, t);
printf("Case %d:\n", ca);
for(int i = 0; i < n; i++)
{
if(cg[i] != -1)
printf("%d\n", ans[cg[i]]);
else
printf("%d\n", ans[i]);
}
}
}
3.静态数组Trie图优化 (2668 ms)
#include <cstdio>
#include <cstring>
#include <queue>
#include <algorithm>
using namespace std;
int const MAXN = 1e6 + 5;
int const MAXM = 505 * 505 ;
char t[MAXN], s[MAXM];
int n, ans[MAXM], cg[MAXM];
struct AC
{
int next[MAXM][26], fail[MAXM], end[MAXM], id[MAXM];
int root, tot;
inline int Newnode()
{
for(int i = 0; i < 26; i++)
next[tot][i] = -1;
end[tot] = 0;
fail[tot] = 0;
return tot ++;
}
inline void Init()
{
tot = 0;
root = Newnode();
}
inline void Insert(char *s, int idx)
{
int len = strlen(s);
int now = root;
for(int i = 0; i < len; i++)
{
int idx = s[i] - 'a';
if(next[now][idx] == -1)
next[now][idx] = Newnode();
now = next[now][idx];
}
if(end[now])
cg[idx] = id[now];
else
{
end[now] = 1;
id[now] = idx;
}
}
inline void Build()
{
queue <int> q;
q.push(root);
while(!q.empty())
{
int now = q.front();
q.pop();
for(int i = 0; i < 26; i++)
{
if(next[now][i] == -1)
{
if(now == root)
next[now][i] = root;
else
next[now][i] = next[fail[now]][i];
}
else
{
if(now == root)
fail[next[now][i]] = root;
else
fail[next[now][i]] = next[fail[now]][i];
q.push(next[now][i]);
}
}
}
}
inline void Query(char *s)
{
int now = root;
int len = strlen(s);
for(int i = 0; i < len; i++)
{
int idx = s[i] - 'a';
while(now != root && next[now][idx] == -1)
now = fail[now];
now = next[now][idx];
int tmp = now;
while(tmp != root)
{
ans[id[tmp]] += end[tmp];
tmp = fail[tmp];
}
}
}
}ac;
int main()
{
int T;
scanf("%d", &T);
for(int ca = 1; ca <= T; ca++)
{
memset(cg, -1, sizeof(cg));
memset(ans, 0, sizeof(ans));
ac.Init();
scanf("%d", &n);
scanf("%s", t);
for(int i = 0; i < n; i++)
{
scanf("%s", s);
ac.Insert(s, i);
}
ac.Build();
ac.Query(t);
printf("Case %d:\n", ca);
for(int i = 0; i < n; i++)
{
if(cg[i] != -1)
printf("%d\n", ans[cg[i]]);
else
printf("%d\n", ans[i]);
}
}
}
#include <cstdio>
#include <cstring>
#include <queue>
#include <algorithm>
using namespace std;
int const MAXN = 1e6 + 5;
int const MAXM = 505 * 505;
char t[MAXN], s[MAXM];
int ans[MAXM], pos[MAXM];
int n;
struct AC
{
int next[MAXM][26], fail[MAXM];
int st[MAXM];
int root, tot, top;
inline int Newnode()
{
memset(next[tot], -1, sizeof(next[tot]));
ans[tot] = 0;
fail[tot] = 0;
return tot ++;
}
inline void Init()
{
top = 0;
tot = 0;
root = Newnode();
}
inline void Insert(char *s, int id)
{
int len = strlen(s);
int now = root;
for(int i = 0; i < len; i++)
{
int idx = s[i] - 'a';
if(next[now][idx] == -1)
next[now][idx] = Newnode();
now = next[now][idx];
}
pos[id] = now;
}
inline void Build()
{
queue <int> q;
q.push(root);
while(!q.empty())
{
int now = q.front();
q.pop();
for(int i = 0; i < 26; i++)
{
if(next[now][i] == -1)
{
if(now == root)
next[now][i] = root;
else
next[now][i] = next[fail[now]][i];
}
else
{
if(now == root)
fail[next[now][i]] = root;
else
fail[next[now][i]] = next[fail[now]][i];
q.push(next[now][i]);
st[++ top] = next[now][i];
}
}
}
}
inline void Query(char *s)
{
int now = root;
int len = strlen(s);
for(int i = 0; i < len; i++)
{
int idx = s[i] - 'a';
now = next[now][idx];
ans[now] ++;
}
while(top)
{
int p = st[top];
ans[fail[p]] += ans[p];
top --;
}
}
}ac;
int main()
{
int T;
scanf("%d", &T);
for(int ca = 1; ca <= T; ca++)
{
ac.Init();
scanf("%d", &n);
scanf("%s", t);
for(int i = 1; i <= n; i++)
{
scanf("%s", s);
ac.Insert(s, i);
}
ac.Build();
ac.Query(t);
printf("Case %d:\n", ca);
for(int i = 1; i <= n; i++)
printf("%d\n", ans[pos[i]]);
}
}