SPOJ694--- DISUBSTR - Distinct Substrings(后缀数组)

Given a string, we need to find the total number of its distinct substrings.
Input

T- number of test cases. T<=20;
Each test case consists of one string, whose length is <= 1000
Output

For each test case output one number saying the number of distinct substrings.
Example

Sample Input:
2
CCCCC
ABABA

Sample Output:
5
9

Explanation for the testcase with string ABABA:
len=1 : A,B
len=2 : AB,BA
len=3 : ABA,BAB
len=4 : ABAB,BABA
len=5 : ABABA
Thus, total number of distinct substrings is 9.

求不同子串个数，每一个子串都是字符串的后缀的前缀，从suffix(sa[0])开始，每次加入一个新的后缀，子串个数加了n - sa[i] + 1个，其中height[i]个是与之前那个后缀的LCP，是重复的，需要去掉
所以加了n - sa[i] + 1 - height[i]个

/*************************************************************************    > File Name: SPOJ694.cpp    > Author: ALex    > Mail: [e-mail]     > Created Time: 2015年03月31日 星期二 18时27分46秒 ************************************************************************/#include <functional>#include <algorithm>#include <iostream>#include <fstream>#include <cstring>#include <cstdio>#include <cmath>#include <cstdlib>#include <queue>#include <stack>#include <map>#include <bitset>#include <set>#include <vector>using namespace std;const double pi = acos(-1.0);const int inf = 0x3f3f3f3f;const double eps = 1e-15;typedef long long LL;typedef pair <int, int> PLL;class SuffixArray{    public:        static const int N = 1010;        int init[N];        int X[N];        int Y[N];        int Rank[N];        int sa[N];        int height[N];        int buc[N];        int size;        void clear()        {            size = 0;        }        void insert(int n)        {            init[size++] = n;        }        bool cmp(int *r, int a, int b, int l)        {            return (r[a] == r[b] && r[a + l] == r[b + l]);        }        void getsa(int m = 256)        {            init[size] = 0;            int l, p, *x = X, *y = Y, n = size + 1;            for (int i = 0; i < m; ++i)            {                buc[i] = 0;            }            for (int i = 0; i < n; ++i)            {                ++buc[x[i] = init[i]];            }            for (int i = 1; i < m; ++i)            {                buc[i] += buc[i - 1];            }            for (int i = n - 1; i >= 0; --i)            {                sa[--buc[x[i]]] = i;            }            for (l = 1, p = 1; l <= n && p < n; m = p, l *= 2)            {                p = 0;                for (int i = n - l; i < n; ++i)                {                    y[p++] = i;                }                for (int i = 0; i < n; ++i)                {                    if (sa[i] >= l)                    {                        y[p++] = sa[i] - l;                    }                }                for (int i = 0; i < m; ++i)                {                    buc[i] = 0;                }                for (int i = 0; i < n; ++i)                {                    ++buc[x[y[i]]];                }                for (int i = 1; i < m; ++i)                {                    buc[i] += buc[i - 1];                }                for (int i = n - 1; i >= 0; --i)                {                    sa[--buc[x[y[i]]]] = y[i];                }                int i;                for (swap(x, y), x[sa[0]] = 0, p = 1, i = 1; i < n; ++i)                {                    x[sa[i]] = cmp(y, sa[i - 1], sa[i], l) ? p - 1 : p++;                }            }        }        void getheight()        {            int h = 0, n = size;            for (int i = 0; i <= n; ++i)            {                Rank[sa[i]] = i;            }            height[0] = 0;            for (int i = 0; i < n; ++i)            {                if (h > 0)                {                    --h;                }                int j = sa[Rank[i] - 1];                for (; i + h < n && j + h < n && init[i + h] == init[j + h]; ++h);                height[Rank[i] - 1] = h;            }        }        void solve()        {            int ans = 0;            for (int i = 1; i <= size; ++i)            {                ans += size - sa[i]  - height[i - 1];            }            printf("%d\n", ans);        }}SA;char str[1010];int main(){    int t;    scanf("%d", &t);    while (t--)    {        scanf("%s", str);        SA.clear();        int len = strlen(str);        int maxs = 0;        for (int i = 0; i < len; ++i)        {            SA.insert((int)str[i]);            maxs = max(maxs, (int)str[i]);        }        SA.getsa(maxs + 1);        SA.getheight();        SA.solve();    }    return 0;}