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  • DISUBSTR

    DISUBSTR - Distinct Substrings

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    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.

    分析:字符串中不同子串的个数;

       建立后缀数组对每一个后缀算贡献即可;

    代码:

    #include <iostream>
    #include <cstdio>
    #include <cstdlib>
    #include <cmath>
    #include <algorithm>
    #include <climits>
    #include <cstring>
    #include <string>
    #include <set>
    #include <map>
    #include <queue>
    #include <stack>
    #include <vector>
    #include <list>
    #define rep(i,m,n) for(i=m;i<=n;i++)
    #define rsp(it,s) for(set<int>::iterator it=s.begin();it!=s.end();it++)
    #define mod 1000000007
    #define inf 0x3f3f3f3f
    #define vi vector<int>
    #define pb push_back
    #define mp make_pair
    #define fi first
    #define se second
    #define ll long long
    #define ld long double
    #define pi acos(-1.0)
    #define pii pair<int,int>
    #define Lson L, mid, ls[rt]
    #define Rson mid+1, R, rs[rt]
    #define sys system("pause")
    #define freopen freopen("in.txt","r",stdin)
    const int maxn=1e3+10;
    using namespace std;
    ll gcd(ll p,ll q){return q==0?p:gcd(q,p%q);}
    ll qpow(ll p,ll q){ll f=1;while(q){if(q&1)f=f*p;p=p*p;q>>=1;}return f;}
    inline ll read()
    {
        ll x=0;int f=1;char ch=getchar();
        while(ch<'0'||ch>'9'){if(ch=='-')f=-1;ch=getchar();}
        while(ch>='0'&&ch<='9'){x=x*10+ch-'0';ch=getchar();}
        return x*f;
    }
    int n,m,k,t,cntA[maxn],cntB[maxn],sa[maxn],lev[maxn],height[maxn],A[maxn],B[maxn],tsa[maxn];
    char ch[maxn];
    void solve()
    {
        for (int i = 0; i < 256; i ++) cntA[i] = 0;
        for (int i = 1; i <= n; i ++) cntA[ch[i]] ++;
        for (int i = 1; i < 256; i ++) cntA[i] += cntA[i - 1];
        for (int i = n; i; i --) sa[cntA[ch[i]] --] = i;
        lev[sa[1]] = 1;
        for (int i = 2; i <= n; i ++)
        {
            lev[sa[i]] = lev[sa[i - 1]];
            if (ch[sa[i]] != ch[sa[i - 1]]) lev[sa[i]] ++;
        }
        for (int l = 1; lev[sa[n]] < n; l <<= 1)
        {
            for (int i = 0; i <= n; i ++) cntA[i] = 0;
            for (int i = 0; i <= n; i ++) cntB[i] = 0;
            for (int i = 1; i <= n; i ++)
            {
                cntA[A[i] = lev[i]] ++;
                cntB[B[i] = (i + l <= n) ? lev[i + l] : 0] ++;
            }
            for (int i = 1; i <= n; i ++) cntB[i] += cntB[i - 1];
            for (int i = n; i; i --) tsa[cntB[B[i]] --] = i;
            for (int i = 1; i <= n; i ++) cntA[i] += cntA[i - 1];
            for (int i = n; i; i --) sa[cntA[A[tsa[i]]] --] = tsa[i];
            lev[sa[1]] = 1;
            for (int i = 2; i <= n; i ++)
            {
                lev[sa[i]] = lev[sa[i - 1]];
                if (A[sa[i]] != A[sa[i - 1]] || B[sa[i]] != B[sa[i - 1]]) lev[sa[i]] ++;
            }
        }
        for (int i = 1, j = 0; i <= n; i ++)
        {
            if (j) j --;
            while (ch[i + j] == ch[sa[lev[i] - 1] + j]) j ++;
            height[lev[i]] = j;
        }
    }
    int main()
    {
        int i,j;
        scanf("%d",&t);
        while(t--)
        {
            scanf("%s",ch+1);
            n=strlen(ch+1);
            solve();
            ll ans=0;
            rep(i,1,n)
            {
                ans+=n-sa[i]+1-height[i];
            }
            printf("%lld
    ",ans);
        }
        //system("Pause");
        return 0;
    }
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  • 原文地址:https://www.cnblogs.com/dyzll/p/6009753.html
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