suffix array SUFFIX

#pragma warning(disable:4786)
#pragma comment(linker, "/STACK:102400000,102400000")
#include<iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
#include<stack>
#include<queue>
#include<map>
#include<set>
#include<vector>
#include<cmath>
#include<string>
#include<sstream>
#define LL long long
#define FOR(i,f_start,f_end) for(int i=f_start;i<=f_end;++i)
#define mem(a,x) memset(a,x,sizeof(a))
#define lson l,m,x<<1
#define rson m+1,r,x<<1|1
using namespace std;
const int INF = 0x3f3f3f3f;
const int mod = 1e9 + 7;
const double PI = acos(-1.0);
const double eps = 1e-8;
const int maxn = 1e4 + 5;
const int maxs = 20;
char s[maxn];
int sa[maxn], t[maxn], t2[maxn], c[maxn], n , m;
int d[maxn][maxs];
int height[maxn], rank[maxn];
void build_sa(int m)
{
    int i, *x = t, *y = t2;
    for ( i = 0; i < m; i++)        c[i] = 0;
    for ( i = 0; i < n; i++)        c[x[i] = s[i]]++;
    for ( i = 1; i < m; i++)    c[i] += c[i - 1];
    for (i = n - 1; i >= 0; i--)    sa[--c[x[i]]] = i;
    for (int k = 1; k <= n; k <<= 1){
        int p = 0;
        for (i = n - k; i < n; i++)
            y[p++] = i;
        for (i = 0; i < n; i++){
            if (sa[i] >= k)
                y [p ++] = sa [i] - k;
        }
        for (i = 0; i < m; i++)    c[i] = 0;
        for (i = 0; i < n; i++)
            c[x[y[i]]]++;
        for (i = 0; i < m; i++)
            c[i] += c[i - 1];
        for (i = n - 1; i >= 0; i--)
            in [ --c [x [y [i]]]] = y [i];
        swap(x, y);
        p = 1;    x[sa[0]] = 0;
        for (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 cmp_suffix(char *pattern, int p)
{
    return strncmp(pattern, s + sa[p], m);
}
int find(char *P)
{
    m = strlen(P);
    if (cmp_suffix(P, 0) < 0)    return -1;
    if (cmp_suffix(P, n - 1)>0)    return -1;
    int left = 0, right = n - 1 , mid;
    while (left <= right){
        mid = left + (right - left) / 2;
        int res = cmp_suffix(P, mid);
        if (!res)    return mid;
        if (res < 0)        right = mid - 1;
        else                left = mid + 1;
    }
    return -1;
}
void getHeight()
{
    int i, j, k = 0;
    for (i = 0; i < n; i++)    rank[sa[i]] = i;
    for (i = 0; i < n; i++){
        if (k)    k--;
         j = sa[rank[i] - 1];
        while (s[i + k] == s[j + k])    k++;
        height[rank[i]] = k;
    }
}
void RMQ_init()
{
    for(int i = 0 ; i<n; i++)       d[i][0] = sa[i];
    for(int j = 1 ; (1<<j) - 1 <=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)
{
    int k = 0;
    while((1<<(k + 1)) <= R - L + 1)    k++;
    return min(d[L][k] , d[R - (1 << k) + 1][k]);
}
intmain ()
{
    char query[1005];
    scanf("%s", s);
    n = strlen(s);
    build_sa('z' + 1 );
    while (scanf("%s", query) == 1){
        int ans = find(query);
        printf("%d\n", ans);
    }
    return 0;
}

Reprinted from https://blog.csdn.net/jijijix/article/details/52319601