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社区首页 >专栏 >挑战程序竞赛系列(73):4.7高度数组(3)

挑战程序竞赛系列(73):4.7高度数组(3)

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发布2018-01-02 11:02:41
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发布2018-01-02 11:02:41
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文章被收录于专栏:机器学习入门机器学习入门

挑战程序竞赛系列(73):4.7高度数组(3)

传送门:POJ 3729: Facer’s String

题意:

公共子串: 给出两个字符串A,B,求满足下列条件的C的个数: 1. C是A的子串 2. C也是B的子串 3. C加上其在A中的后继字符(若在最尾则加上空格字符)不能够在B中出现

其实就是问A中有多少个长度为K的子串在B中刚好存在,且再加上后一个字符形成的子串在B中不存在.

思路: 求出A中存在多少后缀,使得其和B的前缀长度大于等于k,再求出A中存在多少后缀,使得其和B的前缀长度等于k+1,最后两式相减。

所以在>=k的范围内,存在一个B,就可以统计A的后缀个数了,若没有B,则统计也没用。

代码如下:

代码语言:javascript
复制
import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.util.Arrays;
import java.util.Comparator;
import java.util.Map;
import java.util.StringTokenizer;

public class Main{

    String INPUT = "./data/judge/201709/P3729.txt";

    public static void main(String[] args) throws IOException {
        new Main().run();
    }

    class SuffixArray {
        int k = 1;
        int n;
        Integer[] sa;
        int[] rank, tmp;
        int[] lcp;

        SuffixArray(int[] arra) {
            n = arra.length;
            sa = new Integer[n + 1];
            rank = new int[n + 1];
            tmp = new int[n + 1];
            lcp = new int[n];

            for (int i = 0; i <= n; ++i) {
                sa[i] = i;
                rank[i] = i < n ? arra[i] : -1;
            }

            for (k = 1; k <= n; k <<= 1) {
                Arrays.sort(sa, cmp);
                tmp[sa[0]] = 0;
                for (int i = 1; i <= n; ++i) {
                    tmp[sa[i]] = tmp[sa[i - 1]] + (cmp.compare(sa[i - 1], sa[i]) < 0 ? 1 : 0);
                }
                for (int i = 0; i <= n; ++i) {
                    rank[i] = tmp[i];
                }
            }

            // lcp
            int h = 0;
            for (int i = 0; i <= n; ++i)
                rank[sa[i]] = i;
            for (int i = 0; i < n; ++i) {
                int j = sa[rank[i] - 1];
                if (h > 0)
                    h--;
                for (; i + h < n && j + h < n; ++h) {
                    if (arra[i + h] != arra[j + h])
                        break;
                }
                lcp[rank[i] - 1] = h;
            }
        }

        Comparator<Integer> cmp = new Comparator<Integer>() {
            @Override
            public int compare(Integer o1, Integer o2) {
                int i = o1;
                int j = o2;
                if (rank[i] != rank[j])
                    return rank[i] - rank[j];
                else {
                    int ri = i + k <= n ? rank[i + k] : -1;
                    int rj = j + k <= n ? rank[j + k] : -1;
                    return ri - rj;
                }
            }
        };

    }

    void read() {
        while (more()) {
            int m = ni();
            int n = ni();
            int k = ni();
            int[] arra = new int[m + n + 1];
            for (int i = 0; i < m; ++i) {
                arra[i] = ni();
                arra[i] ++;
            }
            arra[m] = 10000 + 8;
            for (int i = 0; i < n; ++i) {
                arra[i + m + 1] = ni();
                arra[i + m + 1] ++;
            }

            SuffixArray sa = new SuffixArray(arra);
            out.println(solve(k, m, sa) - solve(k + 1, m, sa));
        }
    }

    int solve(int k, int m, SuffixArray sa) {
        int ans = 0, A = 0, B = 0;
        for (int i = 0; i < sa.n; i++) {// 统计lcp[i]>=k的连续区间内的A子串
            if (sa.lcp[i] < k) {
                if (B > 0)
                    ans += A;
                A = 0;
                B = 0;
            }
            if (sa.sa[i + 1] < m)
                A++;
            else
                B++;
        }
        return ans;
    }

    FastScanner in;
    PrintWriter out;

    void run() throws IOException {
        boolean oj;
        try {
            oj = !System.getProperty("user.dir").equals("F:\\java_workspace\\leetcode");
        } catch (Exception e) {
            oj = System.getProperty("ONLINE_JUDGE") != null;
        }

        InputStream is = oj ? System.in : new FileInputStream(new File(INPUT));
        in = new FastScanner(is);
        out = new PrintWriter(System.out);
        long s = System.currentTimeMillis();
        read();
        out.flush();
        if (!oj) {
            System.out.println("[" + (System.currentTimeMillis() - s) + "ms]");
        }
    }

    public boolean more() {
        return in.hasNext();
    }

    public int ni() {
        return in.nextInt();
    }

    public long nl() {
        return in.nextLong();
    }

    public double nd() {
        return in.nextDouble();
    }

    public String ns() {
        return in.nextString();
    }

    public char nc() {
        return in.nextChar();
    }

    class FastScanner {
        BufferedReader br;
        StringTokenizer st;
        boolean hasNext;

        public FastScanner(InputStream is) throws IOException {
            br = new BufferedReader(new InputStreamReader(is));
            hasNext = true;
        }

        public String nextToken() {
            while (st == null || !st.hasMoreTokens()) {
                try {
                    st = new StringTokenizer(br.readLine());
                } catch (Exception e) {
                    hasNext = false;
                    return "##";
                }
            }
            return st.nextToken();
        }

        String next = null;

        public boolean hasNext() {
            next = nextToken();
            return hasNext;
        }

        public int nextInt() {
            if (next == null) {
                hasNext();
            }
            String more = next;
            next = null;
            return Integer.parseInt(more);
        }

        public long nextLong() {
            if (next == null) {
                hasNext();
            }
            String more = next;
            next = null;
            return Long.parseLong(more);
        }

        public double nextDouble() {
            if (next == null) {
                hasNext();
            }
            String more = next;
            next = null;
            return Double.parseDouble(more);
        }

        public String nextString() {
            if (next == null) {
                hasNext();
            }
            String more = next;
            next = null;
            return more;
        }

        public char nextChar() {
            if (next == null) {
                hasNext();
            }
            String more = next;
            next = null;
            return more.charAt(0);
        }
    }

    static class ArrayUtils {

        public static void fill(int[][] f, int value) {
            for (int i = 0; i < f.length; ++i) {
                Arrays.fill(f[i], value);
            }
        }

        public static void fill(int[][][] f, int value) {
            for (int i = 0; i < f.length; ++i) {
                fill(f[i], value);
            }
        }

        public static void fill(int[][][][] f, int value) {
            for (int i = 0; i < f.length; ++i) {
                fill(f[i], value);
            }
        }
    }
}
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