uva 11855 - Buzzwords(后缀数组)

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题目链接：uva 11855 - Buzzwords

题目大意：给定一个字符串，输出重复子串长度大于1的重复次数（每种长度只算一个次数最多的），并且按照从大到小输出。

解题思路：后缀数组，处理处后缀数组，然后枚举子串长度，按照长度分段即可。

#include <cstdio>
#include <cstring>
#include <vector>
#include <algorithm>

using namespace std;
const int maxn = 1005;

struct Suffix_Arr {
    int n, s[maxn];
    int SA[maxn], rank[maxn], height[maxn];
    int tmp_one[maxn], tmp_two[maxn], c[maxn];

    vector<int> vec;

    void init (char* str);
    void build_arr(int m);
    void get_fail();

    void solve();
    void check(int k);
}AC;

char str[maxn];

int main () {
    while (gets(str) && strcmp(str, "")) {
        AC.init(str);
        AC.build_arr(27);
        AC.get_fail();
        AC.solve();
        printf("\n");
    }
    return 0;
}

void Suffix_Arr::check(int k) {
    int c = 0, ret = 0;
    for (int i = 0; i <= n; i++) {
        if (height[i] < k) {
            ret = max(ret, c);
            c = 1;
        } else
            c++;
    }

    if (ret > 1)
        vec.push_back(ret);
}

void Suffix_Arr::solve() {
    /*
    for (int i = 0; i < n; i++)
        printf("%d ", SA[i]);
    printf("\n");

    for (int i = 0; i < n; i++)
        printf("%d ", height[i]);
    printf("\n");
    */

    for (int i = 1; i <= n; i++)
        check(i);

    for (int i = 0; i < vec.size(); i++)
        printf("%d\n", vec[i]);
}

void Suffix_Arr::init(char* str) {
    n = 0;
    vec.clear();
    memset(height, 0, sizeof(height));

    int len = strlen(str);
    for (int i = 0; i < len; i++) {
        if (str[i] != ‘ ‘)
            s[n++] = str[i] - ‘A‘ + 1;
    }
    s[n++] = 0;

    /*
    for (int i = 0; i < n; i++)
        printf("%c", s[i] ? ‘A‘ + s[i] - 1 : ‘!‘);
    printf("\n");
    */
}

void Suffix_Arr::get_fail() {
    for (int i = 0; i < n; i++)
        rank[SA[i]] = i;

    int mv = 0;
    for (int i = 0; i < n - 1; i++) {
        if (mv) mv--;

        int j = SA[rank[i] - 1];
        while (s[i+mv] == s[j+mv])
            mv++;
        height[rank[i]] = mv;
    }
}

void Suffix_Arr::build_arr (int m) {

    int *x = tmp_one, *y = tmp_two;

    for (int i = 0; i < m; i++) c[i] = 0;
    for (int i = 0; i < n; i++) c[x[i] = s[i]]++;
    for (int i = 1; i < m; i++) c[i] += c[i-1];
    for (int i = n - 1; i >= 0; i--) SA[--c[x[i]]] = i;

    for (int k = 1; k <= n; k <<= 1) {
        int mv = 0;
        for (int i = n - k; i < n; i++) y[mv++] = i;
        for (int i = 0; i < n; i++) if (SA[i] >= k)
            y[mv++] = SA[i] - k;

        for (int i = 0; i < m; i++) c[i] = 0;
        for (int i = 0; i < n; i++) c[x[y[i]]]++;
        for (int i = 1; i < m; i++) c[i] += c[i-1];
        for (int i = n - 1; i >= 0; i--) SA[--c[x[y[i]]]] = y[i];

        swap(x, y);
        mv = 1;
        x[SA[0]] = 0;
        for (int i = 1; i < n; i++)
            x[SA[i]]  = (y[SA[i-1]] == y[SA[i]] && y[SA[i-1] + k] == y[SA[i] + k] ? mv - 1 : mv++);

        if (mv >= n)
            break;

        m = mv;
    }
}

uva 11855 - Buzzwords(后缀数组)

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原文地址：http://blog.csdn.net/keshuai19940722/article/details/39061343