HDU

题目：给定一个字符串str,求str中至少出现2次且不覆盖的子串的个数

思路：每插入一个字符str[i]，就把str+i+1在当前的SAM中跑一遍，算出每个接待最大匹配长度

代码：

#pragma comment(linker, "/STACK:1024000000,1024000000")#include<iostream>#include<algorithm>#include<ctime>#include<cstdio>#include<cmath>#include<cstring>#include<string>#include<vector>#include<map>#include<set>#include<queue>#include<stack>#include<list>#include<numeric>using namespace std;#define LL long long#define ULL unsigned long long#define INF 0x3f3f3f3f#define mm(a,b) memset(a,b,sizeof(a))#define PP puts("*********************");template<class T> T f_abs(T a){ return a > 0 ? a : -a; }template<class T> T gcd(T a, T b){ return b ? gcd(b, a%b) : a; }template<class T> T lcm(T a,T b){return a/gcd(a,b)*b;}// 0x3f3f3f3f3f3f3f3f//0x3f3f3f3fconst int MAXN = 2050, SIZE = 26;struct SAM {    int len[MAXN], link[MAXN], next[MAXN][SIZE];    int total, last;    inline int newNode(int L) {        len[++total] = L; link[total] = 0;        for(int i = 0; i < SIZE; ++i) next[total][i] = 0;        return total;    }    inline void Add(int c) {        int i, p = last, cur = newNode(len[last] + 1);        for(; p && !next[p][c]; p = link[p]) next[p][c] = cur;        if(!p) link[cur] = 1;//令其指向初始状态        else {            int q = next[p][c];            if(len[q] == len[p] + 1) link[cur] = q;            else {//>                int clone = newNode(len[p] + 1);                for(i = 0; i < SIZE; ++i) next[clone][i] = next[q][i];                link[clone] = link[q];                link[q] = link[cur] = clone;for(; p && next[p][c] == q; p = link[p]) next[p][c] = clone;            }        }        last = cur;    }    void Init () {//根节点是1        total = 0;        last = newNode(0);    }}sam;char str[MAXN];int num[MAXN],idx[MAXN],match[MAXN];void topsort(){    mm(num,0);    for(int i=1;i<=sam.total;i++) num[sam.len[i]]++;    for(int i=1;i<=sam.total;i++) num[i]+=num[i-1];    for(int i=1;i<=sam.total;i++) idx[num[sam.len[i]]--]=i;}void query(char *str){    int now=1,len=0;    for(int i=0;str[i]!='\0';i++){        int c=str[i]-'a';        if(sam.next[now][c]){            len++;            now=sam.next[now][c];        }        else{            while(sam.next[now][c]==0&&now!=0) now=sam.link[now];            if(now==0){                now=1;                len=0;            }            else{                len=sam.len[now]+1;                now=sam.next[now][c];            }        }        match[now]=max(match[now],len);    }}void solve(){    int ans=0;    for(int i=sam.total;i>=1;i--){        int p=idx[i],np=sam.link[p];        if(match[p]) match[np]=sam.len[np];    }    for(int i=1;i<=sam.total;i++){        ans+=max(0,match[i]-sam.len[sam.link[i]]);    }    printf("%d\n",ans);}int main(){    while(~scanf("%s",str)){        if(str[0]=='#')            break;        sam.Init();        mm(match,0);        int L=strlen(str);        for(int i=0;i<=L-2;i++){            sam.Add(str[i]-'a');            query(str+i+1);        }        topsort();        solve();    }    return 0;}