【HDOJ】3948 The Number of Palindromes

后缀数组求不重复回文子串数目。注意dp数组。

/* 3948 */
#include <iostream>
#include <sstream>
#include <string>
#include <map>
#include <queue>
#include <set>
#include <stack>
#include <vector>
#include <deque>
#include <algorithm>
#include <cstdio>
#include <cmath>
#include <ctime>
#include <cstring>
#include <climits>
#include <cctype>
#include <cassert>
#include <functional>
#include <iterator>
#include <iomanip>
using namespace std;
//#pragma comment(linker,"/STACK:102400000,1024000")

#define sti                set<int>
#define stpii            set<pair<int, int> >
#define mpii            map<int,int>
#define vi                vector<int>
#define pii                pair<int,int>
#define vpii            vector<pair<int,int> >
#define rep(i, a, n)     for (int i=a;i<n;++i)
#define per(i, a, n)     for (int i=n-1;i>=a;--i)
#define clr                clear
#define pb                 push_back
#define mp                 make_pair
#define fir                first
#define sec                second
#define all(x)             (x).begin(),(x).end()
#define SZ(x)             ((int)(x).size())
#define lson            l, mid, rt<<1
#define rson            mid+1, r, rt<<1|1

const int INF = 0x3f3f3f3f;
const int maxl = 2e5+5;
const int maxn = 4e5+5;
char s[maxl], ss[maxl];
int a[maxn];
int height[maxn], rrank[maxn], sa[maxn];
int wa[maxn], wb[maxn], wc[maxn], wv[maxn];
bool visit[maxn];
int dp[19][maxn];

bool cmp(int *r, int a, int b, int l) {
    return r[a]==r[b] && r[a+l]==r[b+l];
}

void da(int *r, int *sa, int n, int m) {
    int i, j, *x=wa, *y=wb, *t, p;

    for (i=0; i<m; ++i) wc[i] = 0;
    for (i=0; i<n; ++i) wc[x[i]=r[i]]++;
    for (i=1; i<m; ++i) wc[i] += wc[i-1];
    for (i=n-1; i>=0; --i) sa[--wc[x[i]]]=i;
    for (j=1,p=1; p<n; j*=2, m=p) {
        for (p=0,i=n-j; i<n; ++i) y[p++] = i;
        for (i=0; i<n; ++i) if (sa[i] >= j) y[p++] = sa[i] - j;
        for (i=0; i<n; ++i) wv[i] = x[y[i]];
        for (i=0; i<m; ++i) wc[i] = 0;
        for (i=0; i<n; ++i) wc[wv[i]]++;
        for (i=1; i<m; ++i) wc[i] += wc[i-1];
        for (i=n-1; i>=0; --i) sa[--wc[wv[i]]] = y[i];
        for (t=x,x=y,y=t, x[sa[0]]=0, p=1,i=1; i<n; ++i)
            x[sa[i]] = cmp(y, sa[i-1], sa[i], j) ? p-1:p++;
    }
}

void calheight(int *r, int *sa, int n) {
    int i, j, k = 0;

    for (i=1; i<=n; ++i) rrank[sa[i]] = i;
    for (i=0; i<n; height[rrank[i++]]=k)
    for (k?k--:0, j=sa[rrank[i]-1]; r[i+k]==r[j+k]; ++k) ;
}

void printSa(int n) {
    for (int i=1; i<=n; ++i)
        printf("%d ", sa[i]);
    putchar('
');
}

void printHeight(int n) {
    for (int i=1; i<=n; ++i)
        printf("%d ", height[i]);
    putchar('
');
}

void printRank(int n) {
    for (int i=1; i<=n; ++i)
        printf("%d ", rrank[i]);
    putchar('
');
}

void init_RMQ(int n) {
    int i, j;

    for (i=1; i<=n; ++i)
        dp[0][i] = height[i];
    dp[0][1] = INF;
    for (j=1; (1<<j)<=n; ++j)
        for (i=1; i+(1<<j)-1<=n; ++i)
            dp[j][i] = min(dp[j-1][i], dp[j-1][i+(1<<(j-1))]);
}

int RMQ(int l, int r) {
    if (l > r)
        swap(l, r);

    ++l;
    int k = 0;

    while (1<<(k+1) <= r-l+1)
        ++k;

    return min(dp[k][l], dp[k][r-(1<<k)+1]);
}

void solve() {
    int len = strlen(s);
    int nn = len * 2 + 1, n, nn2 = nn * 2;
    int l = 0;

    rep(i, 0, len) {
        a[l] = a[nn2-l] = 2;
        ++l;
        a[l] = a[nn2-l] = s[i]-'a'+3;
        ++l;
    }
    a[l] = a[nn2-l] = 2;
    a[nn] = 1;
    a[nn2+1] = 0;

    n = nn2 + 1;
    da(a, sa, n+1, 32);
    calheight(a, sa, n);
    
    #ifndef ONLINE_JUDGE
        // printSa(n);
        // printHeight(n);
    #endif

    init_RMQ(n);

    int ans = 0, mn = 0, tmp;

    memset(visit, false, sizeof(visit));
    rep(i, 2, n+1) {
        mn = min(mn, height[i]);
        if (visit[nn2-sa[i]]) {
            tmp = RMQ(rrank[sa[i]], rrank[nn2-sa[i]]);
            if (tmp > mn) {
                ans += (tmp - mn) >> 1;
                mn = tmp;
            }
        } else {
            visit[sa[i]] = true;
        }
    }

    printf("%d
", ans);
}

int main() {
    ios::sync_with_stdio(false);
    #ifndef ONLINE_JUDGE
        freopen("data.in", "r", stdin);
        freopen("data.out", "w", stdout);
    #endif

    int t;

    scanf("%d", &t);
    rep(tt, 1, t+1) {
        scanf("%s", s);
        printf("Case #%d: ", tt);
        solve();
    }

    #ifndef ONLINE_JUDGE
        printf("time = %d.
", (int)clock());
    #endif

    return 0;
}

数据生成器。

from random import randint, shuffle
import shutil
import string


def GenDataIn():
    with open("data.in", "w") as fout:
        t = 20
        bound = 10**3
        lc = list(string.lowercase)
        fout.write("%d
" % (t))
        for tt in xrange(t):
            length = randint(50, 105)
            line = ""
            for i in xrange(length):
                idx = randint(0, 5)
                line += lc[idx]
            fout.write("%s
" % (line))
            
        
                
def MovDataIn():
    desFileName = "F:eclipse_prjworkspacehdojdata.in"
    shutil.copyfile("data.in", desFileName)

    
if __name__ == "__main__":
    GenDataIn()
    MovDataIn()