poj 3294 Girls' research (manacher,回文串)

 1#include <cstdio>
 2#include <cstring>
 3#include <iostream>
 4#include <algorithm>
 5#include <vector>
 6#include <queue>
 7#include <set>
 8#include <map>
 9#include <string>
10#include <cmath>
11#include <cstdlib>
12#include <ctime>
13#define fst first
14#define sec second
15#define lson l,m,rt<<1
16#define rson m+1,r,rt<<1|1
17#define ms(a,x) memset(a,x,sizeof(a))
18typedef long long LL;
19#define pi pair < int ,int >
20#define MP make_pair

1using namespace std;
2const double eps = 1E-8;
3const int dx4[4]={1,0,0,-1};
4const int dy4[4]={0,-1,1,0};
5const int inf = 0x3f3f3f3f;
6const int N=4E5+7;
7char st[N],st2[N];
8int p[N];
9char ch;

1void manacher(char *s)
2{
3    int len = strlen(s);

1    for ( int i = len ;  i>= 0 ; i--)
2    {
3    s[i*2+2] = s[i];
4    s[i*2+1] = '#';
5    }

1    int id = 0 ;
2    int maxlen = 0 ;
3    int center = 0 ;
4    s[0]='%';
5    for ( int i = 2 ; i < 2*len+1 ; i++)
6    {
7    if (id+p[id]>i) p[i] = min(p[2*id-i],p[id]+id-i);
8    else p[i] = 1;

 1    if (id+p[id]<i+p[i]) id = i;
 2    if (p[i]>maxlen)
 3    {
 4        maxlen = p[i];
 5        center = i;
 6    }
 7    }
 8    int ans = (maxlen-1);
 9   // cout<<"ans:"<<ans<<" center:"<<center<<endl;
10    if (ans<2)
11    {
12    puts("No solution!");
13    }
14    else
15    {
16    int left = center/2-1-ans/2+(ans%2==0);
17    int right = center/2-1+ans/2;
18    printf("%d %d\n",left,right);
19    for ( int  i = left ; i <= right ; i++) printf("%c",st2[i]);
20    printf("\n");
21    }

1}
2int main()
3{
4    #ifndef  ONLINE_JUDGE 
5    freopen("code/in.txt","r",stdin);
6  #endif

 1    while (scanf("%c %s\n",&ch,st)!=EOF)
 2    {
 3        int k = ch-'a';
 4        int len = strlen(st);
 5        for ( int i = 0 ; i < len ; i++)
 6        {
 7        int tmp = (st[i]-'a'-k+26);
 8        st[i] = char(tmp+'a');
 9        st2[i] = st[i];
10        }
11    //    cout<<"st:"<<st<<endl;
12        manacher(st);
13    }

1  #ifndef ONLINE_JUDGE  
2  fclose(stdin);
3  #endif
4    return 0;
5}

1#include <bits/stdc++.h>
2#define fst first
3#define sec second
4#define lson l,m,rt<<1
5#define rson m+1,r,rt<<1|1
6#define ms(a,x) memset(a,x,sizeof(a))
7typedef long long LL;
8#define pi pair < int ,int >
9#define MP make_pair

 1using namespace std;
 2const double eps = 1E-8;
 3const int dx4[4]={1,0,0,-1};
 4const int dy4[4]={0,-1,1,0};
 5const int inf = 0x3f3f3f3f;
 6const int N=5E5+79;
 7int t[2*N];
 8char st[N];
 9int p[2*N];  //p[i]为以第i个位置的字符为中心的回文串的半径长，默认为1.
10vector<int>vec[N];
11int a[2*N];
12char Ma[2*N];
13int Mp[2*N];
14int Manacher( char *s)
15{
16    int len = strlen(s);
17    int id = 0; //id表示之前位置的能延伸到最远位置的字符串的中心位置。
18    int maxlen = 0 ;  //maxlen是为了更新答案而用。。。就是记录了一个最大值。。。
19    int mx = 0 ;//mx为当前位置之前的回文串能延伸到的最远位置 即：max(p[j]+j) (j<i)
20                //如果知道之前能延伸到最远位置的字符串的中心位置的下标为id，那么就是p[id]+id;
21    for ( int i = len ; i >= 0 ; i--)  //插入'#'是为了将字符串长度奇偶性不同的统一考虑。
22    {
23        Ma[i+i+2] = s[i];
24        Ma[i+i+1] = '#';
25    }
26    Ma[0]='*'; //s[0] ='*'以及用字符数组最后默认的s[len+len+2]='\0'是为了下面while 循环的时候不溢出。。
27                //两边的字符一定要不一样。。用string的话记得两边都加字符。。。
28    for ( int i = 2 ; i < 2*len+1 ; i++)
29    {
30        if (Mp[id]+id>i) Mp[i] = min(Mp[2*id-i],Mp[id]+id-i);
31        else Mp[i] = 1;
32        while (Ma[i-Mp[i]]==Ma[i+Mp[i]]) Mp[i]++;
33        if (id+Mp[id]<i+Mp[i]) id = i;
34        if (maxlen<Mp[i]) maxlen = p[i];
35    }
36    return 2*len+2;
37    //这道题是问最长回文串的长度。。。如果是问回文串是什么的话。。。根据id和maxlen也可以构造出来。。。
38}

 1int lowbit( int x) { return x&(-x);}
 2void update ( int x,int delta)
 3{
 4    for ( int i = x; i < 2*N ; i+=lowbit(i))
 5    t[i]+=delta;
 6}
 7int Sum( int x)
 8{
 9    int res = 0 ;
10    for ( int i = x ; i >= 1 ; i-=lowbit(i))
11    res = res + t[i];
12    return res;
13}
14int main()
15{
16        #ifndef  ONLINE_JUDGE 
17       freopen("./in.txt","r",stdin);
18  #endif
19    int T;
20    cin>>T;
21    while (T--)
22    {
23        ms(t,0);
24        for ( int i = 0 ; i < N ; i++) vec[i].clear();
25        scanf("%s",st);
26        int n = strlen(st);
27        int len = Manacher(st);
28        int k = 1;
29        for ( int i = 2 ; i < len ; i+=2)
30        {
31        a[k] = Mp[i]/2-1;

 1        printf("k:%d a[k]：%d p[i]:%d\n",k,a[k],Mp[i]);
 2        vec[k-a[k]].push_back(k);
 3        k++;
 4        }
 5        LL ans = 0 ;
 6        for ( int i = 1 ; i <= n  ; i++)
 7        {
 8//      cout<<"a[i]:"<<a[i]<<endl;
 9        for ( int j = 0 ; j < vec[i].size() ; j++)
10            update(vec[i][j],1);
11        ans += Sum(min(i+a[i],n)) -Sum(i);
12        }
13//      cout<<Sum(2*N)<<endl;
14        cout<<ans<<endl;
15    }
16  #ifndef ONLINE_JUDGE  
17  fclose(stdin);
18  #endif
19    return 0;
20}