不相同子串的个数

题目链接：https://cn.vjudge.net/contest/318888#problem/C

题意：给定一个字符串，求不相同的子串个数。

思路：

但是这里有一个点需要小心：

因为我们求后缀数组的时候为了防止越界的问题的话，会让最后一个为0(一个最小的从未出现的值)。这样的话我们的末尾会多一个0，所以如果是这样我们推出来的公式应该是

(n-1)-sa[k]+1-height[k]

#include <stdio.h>
#include <iostream>
#include <algorithm>
#include <string.h>
#include <stdlib.h>
#include <math.h>
#include <queue>
#include <set>

#define INF 0x3f3f3f3f
#define pii pair<int,int>
#define LL long long
typedef unsigned long long ull;
using namespace std;
const int maxn = 1e5+10;


char s[maxn];
int sa[maxn],t[maxn],t2[maxn],c[maxn];
int height[maxn],Rank[maxn];

void build_sa(int n,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=1;i<m;i++){
            c[i] += c[i-1];
        }
        for (i=n-1;i>=0;i--){
            sa[--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;
    }
}

void getHeight(int n){
    int i,j,k=0;
    for (i=1;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 solve(int n){
    int ans = 0;
    for (int i=1;i<=n;i++){
        ans += n-sa[i]-height[i];
    }
    printf("%d
",ans);
}


int main(){
    int T;
    scanf("%d",&T);
    while (T--){
        scanf("%s",s);
        int len = strlen(s);
        build_sa(len+1,200);
        getHeight(len);
        solve(len);
    }
    return 0;
}

#include <stdio.h>
#include <iostream>
#include <algorithm>
#include <string.h>
#include <stdlib.h>
#include <math.h>
#include <queue>
#include <set>

#define INF 0x3f3f3f3f
#define pii pair<int,int>
#define LL long long
using namespace std;
typedef unsigned long long ull;
const int MAXN = 2e5 + 10;

int wa[MAXN], wb[MAXN], wv[MAXN], ws_[MAXN];
int sta[MAXN];
int cnt[MAXN];
void Suffix(int *r, int *sa, int n, int m)
{
    int i, j, k, *x = wa, *y = wb, *t;
    for(i = 0; i < m; ++i) ws_[i] = 0;
    for(i = 0; i < n; ++i) ws_[x[i] = r[i]]++;
    for(i = 1; i < m; ++i) ws_[i] += ws_[i - 1];
    for(i = n - 1; i >= 0; --i) sa[--ws_[x[i]]] = i;
    for(j = 1, k = 1; k < n; j *= 2, m = k)
    {
        for(k = 0, i = n - j; i < n; ++i) y[k++] = i;
        for(i = 0; i < n; ++i) if(sa[i] >= j) y[k++] = sa[i] - j;
        for(i = 0; i < n; ++i) wv[i] = x[y[i]];
        for(i = 0; i < m; ++i) ws_[i] = 0;
        for(i = 0; i < n; ++i) ws_[wv[i]]++;
        for(i = 1; i < m; ++i) ws_[i] += ws_[i - 1];
        for(i = n - 1; i >= 0; --i) sa[--ws_[wv[i]]] = y[i];
        t = x;
        x = y;
        y = t;
        for(x[sa[0]] = 0, i = k = 1; i < n; ++i)
            x[sa[i]] = (y[sa[i - 1]] == y[sa[i]] && y[sa[i - 1] + j] == y[sa[i] + j]) ? k - 1 : k++;
    }
}
int Rank[MAXN], height[MAXN], sa[MAXN], r[MAXN];
char s[MAXN];
int indexx[MAXN],vis[200];
void calheight(int *r,int *sa,int n)
{
    int i,j,k=0;
    for(i=1; i<=n; i++)Rank[sa[i]]=i;
    for(i=0; i<n; height[Rank[i++]]=k)
        for(k?k--:0,j=sa[Rank[i]-1]; r[i+k]==r[j+k]; k++);
}

bool check(int x,int n,int k){
    int tot = 1;
    for (int i=1;i<n;i++){
        if (height[i]>=x){
            tot++;
        }
        else {
            if (tot>=k)
                return true;
            tot = 1;
        }
    }
    return tot>=k;
}



int main(){
    int T;
    scanf("%d",&T);
    while (T--){
        scanf("%s",s);
        int n = strlen(s);
        for (int i=0;i<n;i++){
            r[i] = s[i];
        }
        r[n] = 0;
        Suffix(r,sa,n+1,300);
        calheight(r,sa,n);
        LL ans = 0;
        for (int i=1;i<=n;i++){
            ans += (n-sa[i]-height[i]);
        }
        printf("%lld
",ans);
    }
    return 0;
}