后缀数组 + LCP加速多模式匹配算法 O(m+logn)

#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
#include <vector>
using namespace std;
const int maxn = 200;
char s[maxn];
int sa[maxn], t[maxn], t2[maxn], c[maxn];
int n;
//构造字符串s的后缀数组， 每个字符值必须为0 ～ m-1
void build_sa(int m) {
    int *x = t, *y = t2;
    //基数排序
    for(int i = 0; i < m; i++) c[i] = 0;
    for(int i = 0; i < n; i++) c[x[i] = s[i]]++;
    for(int i = 1; i < m; i++) c[i] += c[i-1];
    for(int i = n-1; i >= 0; i--) sa[--c[x[i]]] = i;
    for(int k = 1; k <= n; k <<= 1) {
        int p = 0;
        //直接利用sa数组排序第二关键字
        for(int i = n-k; i < n; i++) y[p++] = i;
        for(int i = 0; i < n; i++) if(sa[i] >= k) y[p++] = sa[i] - k;
        //基数排序第一关键字
        for(int i = 0; i < m; i++) c[i] = 0;
        for(int i = 0; i < n; i++) c[x[y[i]]]++;
        for(int i = 1; i < m; i++) c[i] += c[i-1];
        for(int i = n-1; i>= 0; i--) sa[--c[x[y[i]]]] = y[i];
        //根据sa和y数组计算新的x数组
        swap(x, y);
        p = 1;
        x[sa[0]] = 0;
        for(int i = 1; i < n; i++)
            x[sa[i]] = (y[sa[i-1]] == y[sa[i]] && y[sa[i-1]+k] == y[sa[i]+k] ? p-1 : p++);
        if(p >= n) break;
        m = p;
    }
}

int rank_[maxn]; //rank[i]代表后缀i在sa数组中的下标
int height[maxn]; //height[i] 定义为sa[i-1] 和 sa[i] 的最长公共前缀
//后缀j和k的LCP长度等于RMQ(height, rank[j]+1, rank[k])
void get_height() {
    int i, j, k = 0;
    for(int i = 0; i < n; i++) rank_[sa[i]] = i;
    for(int i = 0; i < n; i++) {
        if(!rank_[i]) continue;
        int j = sa[rank_[i]-1];
        if(k) k--;
        
        while(s[i+k] == s[j+k]) k++;
        height[rank_[i]] = k;
    }
}
int d[maxn][50];
void rmq_init() {
    for(int i = 0; i < n; i++) d[i][0] = height[i];
    for(int j = 1; (1<<j) <= n; j++)
        for(int i = 0; i + (1<<j) - 1 < n; i++)
            d[i][j] = min(d[i][j-1], d[i+(1<<(j-1))][j-1]);
}
int rmq(int l, int r) {
    if(l == r) return n-l;
    if(rank_[l] > rank_[r]) swap(l, r);
    int L = rank_[l]+1;
    int R = rank_[r];
    int k = 0;
    while((1<<(k+1)) <= R-L+1) k++;
    return min(d[L][k], d[R-(1<<k)+1][k]);
}
//LCP加速多模式匹配
int m;
int cmp_suffix(char* P, int p, int c,int &k) {
    k = 0;
    int i;
    for(i = 0; P[c+i] == s[sa[p]+c+i]; i++) {
        if(P[c+i] == '')
            return 0;
        k++;
    }
    if(P[c+i] == '')
        return 0;
    return P[c+i] - s[sa[p]+c+i];
}
vector<int> A; 
void b_search(char*P, int L, int R) { 
    int k;
    if(cmp_suffix(P, L, 0, k) < 0) return ;
    if(cmp_suffix(P, R, 0, k) > 0) return ;
    int c = 0, rr = 0;
    int lst = -1;
    k = 0;
    while(R >= L) {
        int M = L + (R-L)/2;
        if(lst != -1) c = rmq(lst, sa[M]);
        if(c <= k) {
            int res = cmp_suffix(P, M, c, k);
            rr = res;
            if(!res) {
                A.push_back(sa[M]);
                b_search(P, L, M-1);
                b_search(P, M+1, R);
                return;
            }
            lst = sa[M];
            if(res < 0) R = M-1; else L = M+1;
        }
        else if(rr < 0)R = M-1;
        else L = M+1;
    }
}
void find(char* P) {  //找到全部的匹配位置存入A数组中
    A.clear();
    m = strlen(P);
    int L = 0, R = n-1;
    b_search(P, L, R);
    sort(A.begin(), A.end());
}