[whu 1564]接尾辞配列

http://acm.whu.edu.cn/land/problem/detail?problem_id=1564
構想:まず列をコピーして、末尾にマークを付けて、接尾辞の配列を走って、スキャンしてokになります(接尾辞を後半にフィルタします).

  1 #pragma comment(linker, "/STACK:10240000,10240000")

  2 

  3 #include <iostream>

  4 #include <cstdio>

  5 #include <algorithm>

  6 #include <cstdlib>

  7 #include <cstring>

  8 #include <map>

  9 #include <queue>

 10 #include <deque>

 11 #include <cmath>

 12 #include <vector>

 13 #include <ctime>

 14 #include <cctype>

 15 #include <set>

 16 #include <bitset>

 17 #include <functional>

 18 #include <numeric>

 19 #include <stdexcept>

 20 #include <utility>

 21 

 22 using namespace std;

 23 

 24 #define mem0(a) memset(a, 0, sizeof(a))

 25 #define mem_1(a) memset(a, -1, sizeof(a))

 26 #define lson l, m, rt << 1

 27 #define rson m + 1, r, rt << 1 | 1

 28 #define define_m int m = (l + r) >> 1

 29 #define rep_up0(a, b) for (int a = 0; a < (b); a++)

 30 #define rep_up1(a, b) for (int a = 1; a <= (b); a++)

 31 #define rep_down0(a, b) for (int a = b - 1; a >= 0; a--)

 32 #define rep_down1(a, b) for (int a = b; a > 0; a--)

 33 #define all(a) (a).begin(), (a).end()

 34 #define lowbit(x) ((x) & (-(x)))

 35 #define constructInt4(name, a, b, c, d) name(int a = 0, int b = 0, int c = 0, int d = 0): a(a), b(b), c(c), d(d) {}

 36 #define constructInt3(name, a, b, c) name(int a = 0, int b = 0, int c = 0): a(a), b(b), c(c) {}

 37 #define constructInt2(name, a, b) name(int a = 0, int b = 0): a(a), b(b) {}

 38 #define pchr(a) putchar(a)

 39 #define pstr(a) printf("%s", a)

 40 #define sstr(a) scanf("%s", a)

 41 #define sint(a) scanf("%d", &a)

 42 #define sint2(a, b) scanf("%d%d", &a, &b)

 43 #define sint3(a, b, c) scanf("%d%d%d", &a, &b, &c)

 44 #define pint(a) printf("%d
", a)

 45 #define test_print1(a) cout << "var1 = " << a << endl

 46 #define test_print2(a, b) cout << "var1 = " << a << ", var2 = " << b << endl

 47 #define test_print3(a, b, c) cout << "var1 = " << a << ", var2 = " << b << ", var3 = " << c << endl

 48 

 49 typedef double db;

 50 typedef long long LL;

 51 typedef pair<int, int> pii;

 52 typedef multiset<int> msi;

 53 typedef set<int> si;

 54 typedef vector<int> vi;

 55 typedef map<int, int> mii;

 56 

 57 const int dx[8] = {0, 0, -1, 1, 1, 1, -1, -1};

 58 const int dy[8] = {-1, 1, 0, 0, 1, -1, 1, -1 };

 59 const int maxn = 1e6 + 7;

 60 const int md = 1e9 + 7;

 61 const int inf = 1e9 + 7;

 62 const LL inf_L = 1e18 + 7;

 63 const double pi = acos(-1.0);

 64 const double eps = 1e-6;

 65 

 66 template<class T>T gcd(T a, T b){return b==0?a:gcd(b,a%b);}

 67 template<class T>bool max_update(T &a,const T &b){if(b>a){a = b; return true;}return false;}

 68 template<class T>bool min_update(T &a,const T &b){if(b<a){a = b; return true;}return false;}

 69 template<class T>T condition(bool f, T a, T b){return f?a:b;}

 70 template<class T>void copy_arr(T a[], T b[], int n){rep_up0(i,n)a[i]=b[i];}

 71 int make_id(int x, int y, int n) { return x * n + y; }

 72 

 73 

 74 ///          ，            (         )，

 75 ///              （                     ）,

 76 ///  n        +1，  n-1 "  "，sa[0]  n-1。

 77 struct SuffixArray {

 78     int n;

 79     int arr[6][maxn];

 80     int *sa, *x, *y, *c, *rnk, *height;

 81     SuffixArray() { sa = arr[0]; x = arr[1]; y = arr[2]; c = arr[3]; rnk = arr[4]; height = arr[5]; }

 82     void resize(int nn) {  n = nn; mem0(arr[0]); }

 83     void build_sa(int s[], int m) { // m is biger than the max value of char

 84         rep_up0(i, m) c[i] = 0;

 85         rep_up0(i, n) c[x[i] = s[i]]++;

 86         rep_up1(i, m - 1) c[i] += c[i - 1];

 87         rep_down0(i, n) sa[--c[x[i]]] = i;

 88         for (int k = 1; k <= n; k <<= 1) {

 89             int p = 0;

 90             for (int i = n - k; i < n; i++) y[p++] = i;

 91             rep_up0(i, n) if (sa[i] >= k) y[p++] = sa[i] - k;

 92             rep_up0(i, m) c[i] = 0;

 93             rep_up0(i, n) c[x[y[i]]]++;

 94             rep_up0(i, m) c[i] += c[i - 1];

 95             rep_down0(i, n) sa[--c[x[y[i]]]] = y[i];

 96             swap(x, y);

 97             p = 1; x[sa[0]] = 0;

 98             for (int i = 1; i < n; i++) {

 99                 x[sa[i]] = y[sa[i - 1]] == y[sa[i]] && y[sa[i - 1] + k] == y[sa[i] + k]? p - 1 : p++;

100             }

101             if (p >= n) break;

102             m = p;

103         }

104     }

105     void build_height(int s[]) {

106         int k = 0;

107         rep_up0(i, n) rnk[sa[i]] = i;

108         rep_up0(i, n) {

109             if (k) k--;

110             int j = sa[rnk[i] - 1];

111             while (s[i + k] == s[j + k]) k++;

112             height[rnk[i]] = k;

113         }

114     }

115 };

116 

117 SuffixArray sa;

118 char s[maxn];

119 int ss[maxn];

120 

121 int main() {

122     //freopen("in.txt", "r", stdin);

123     int n, k;

124     while (cin >> n >> k) {

125         scanf("%s", s);

126         rep_up0(i, n) ss[i + n] = ss[i] = s[i];

127         ss[2 * n] = 0;

128         int len = n * 2 + 1;

129         sa.resize(len);

130         sa.build_sa(ss, 128);

131         int cnt = 0;

132         for (int i = 1; i < len; i++) {

133             if (sa.sa[i] < n) {

134                 cnt++;

135                 if (cnt == k) {

136                     int x = sa.sa[i];

137                     if (x == 0) x = n;

138                     cout << x << endl;

139                     break;

140                 }

141             }

142         }

143     }

144     return 0;

145 }

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