hdu1403 poj2774(後綴數組)

後綴數組的簡單應用

 

推薦羅穗騫的論文，我的主要代碼也是按照論文上來的。

 

兩個題基本一樣可以用同樣的代碼通過

 

代碼如下：

/* * File: main.cpp * Author: liuwei * * Created on October 14, 2010, 7:30 PM */ #include <cstdlib> #include <cstdio> #include <iostream> #include <cstring> using namespace std; #define MAXN 200010 char str[100010]; int arr[MAXN]; int wa[MAXN], wb[MAXN], wv[MAXN], tmp[MAXN]; int sa[MAXN]; //index range 1~n value range 0~n-1 int 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, p, *x = wa, *y = wb, *ws = tmp; for (i = 0; i < m; ++i) ws[i] = 0; for (i = 0; i < n; ++i) ws[x[i] = r[i]]++; for (i = 1; i < m; ++i) ws[i] += ws[i - 1]; for (i = n - 1; i >= 0; --i) sa[--ws[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) ws[i] = 0; for (i = 0; i < n; ++i) ws[wv[i]]++; for (i = 1; i < m; ++i) ws[i] += ws[i - 1]; for (i = n - 1; i >= 0; --i) sa[--ws[wv[i]]] = y[i]; for (swap(x, y), p = 1, x[sa[0]] = 0, i = 1; i < n; ++i) x[sa[i]] = cmp(y, sa[i - 1], sa[i], j) ? p - 1 : p++; } return; } int rank[MAXN]; //index range 0~n-1 value range 1~n int height[MAXN]; //index from 1 (height[1] = 0) void calHeight(int *r, int *sa, int n) { int i, j, k = 0; for (i = 1; i <= n; ++i) rank[sa[i]] = i; for (i = 0; i < n; height[rank[i++]] = k) for (k ? k-- : 0, j = sa[rank[i] - 1]; r[i + k] == r[j + k]; ++k); return; } int main(int argc, char** argv) { while (EOF != scanf("%s", str)) { int p, n = 0; int len = strlen(str); p = len; for (n = 0; n < len; ++n) arr[n] = str[n] - 96; arr[n++] = 27; scanf("%s", str); len = strlen(str); int i; for (i = 0; i < len; ++i, ++n) arr[n] = str[i] - 96; arr[n] = 0; da(arr, sa, n + 1, 28); calHeight(arr, sa, n); int ret(0); for (i = 2; i <= n; ++i) { if ((sa[i] > p && sa[i - 1] < p) || (sa[i] < p && sa[i - 1] > p)) ret = max(ret, height[i]); } printf("%d/n", ret); } return 0; }