SPOJ DISUBSTR（后缀数组）

传送门：DISUBSTR

题意：给定一个字符串，求不相同的子串。

分析：对于每个sa[i]贡献n-a[i]个后缀，然后减去a[i]与a[i-1]的公共前缀height[i]，则每个a[i]贡献n-sa[i]-height[i]个不同子串。

#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
#include <queue>
using namespace std;
const int maxn = ;

int sa[maxn];
int t1[maxn], t2[maxn], c[maxn];
int rank[maxn], height[maxn];
int s[maxn];
char str[maxn];

void build_sa(int s[], int n, int m) {
    int i, j, p, *x = t1, *y = t2;
    for (i = ; i < m; i++) c[i] = ;
    for (i = ; i < n; i++) c[x[i] = s[i]]++;
    for (i = ; i < m; i++) c[i] += c[i-];
    for (i = n-; i >= ; i--) sa[--c[x[i]]] = i;

    for (j = ; j <= n; j <<= ) {
        p = ;
        for (i = n-j; i < n; i++) y[p++] = i;
        for (i = ; i < n; i++)
            if (sa[i] >= j)
                y[p++] = sa[i] - j;
        for (i = ; i < m; i++) c[i] = ;
        for (i = ; i < n; i++) c[x[y[i]]]++;
        for (i = ; i < m; i++) c[i] += c[i-];
        for (i = n-; i >= ; i--) sa[--c[x[y[i]]]] = y[i];

        swap(x, y);
        p = , x[sa[]] = ;
        for (i = ; i < n; i++)
            x[sa[i]] = y[sa[i-]] == y[sa[i]] && y[sa[i-]+j] == y[sa[i]+j] ? p- : p++;

        if (p >= n) break;
        m = p;
    }
}

void getHeight(int s[],int n) {
    int i, j, k = ;
    for (i = ; i <= n; i++)
        rank[sa[i]] = i;
    for (i = ; i < n; i++) {
        if (k) k--;
        j = sa[rank[i]-];
        while (s[i+k] == s[j+k]) k++;
        height[rank[i]]=k;
    }
}
int main() {
    int T;
    scanf("%d", &T);
    while (T--) {
        scanf("%s", str);
        int n = strlen(str);
        for (int i = ; i <= n; i++)
            s[i] = str[i];
        build_sa(s, n+, );
        getHeight(s, n);
        int ans = ;
        for (int i = ; i <= n; i++)
            ans += n - sa[i] - height[i];
        printf("%d\n", ans);
    }
    return ;
}