标签:style http color os io for ar 代码 amp
题意:一个字符串如果形如UGU,的形式,G的长度为L,那么称这个字符串为L串,给定一个字符串,问这个字符串子串为g串的个数
思路:做这题前先做了POJ3693,有一个思想就是枚举长度分段,这样的话对于一个U长度为l的而言,只要在当前位置和当前位置之后(l + g)的位置分别向前向后找lcp,两个lcp加起来的长度减去l就是可以可以的种数,累加起来就是答案
代码:
#include <cstdio> #include <cstring> #include <algorithm> using namespace std; typedef long long ll; const int MAXLEN = 100005; struct Suffix { int s[MAXLEN]; int sa[MAXLEN], t[MAXLEN], t2[MAXLEN], c[MAXLEN], n; int rank[MAXLEN], height[MAXLEN]; int best[MAXLEN][20]; int g, len; char str[MAXLEN]; void build_sa(int m) { n++; int i, *x = t, *y = t2; for (i = 0; i < m; i++) c[i] = 0; for (i = 0; i < n; i++) c[x[i] = s[i]]++; for (i = 1; i < m; i++) c[i] += c[i - 1]; for (i = n - 1; i >= 0; i--) sa[--c[x[i]]] = i; for (int k = 1; k <= n; k <<= 1) { int p = 0; for (i = n - k; i < n; i++) y[p++] = i; for (i = 0; i < n; i++) if (sa[i] >= k) y[p++] = sa[i] - k; for (i = 0; i < m; i++) c[i] = 0; for (i = 0; i < n; i++) c[x[y[i]]]++; for (i = 0; i < m; i++) c[i] += c[i - 1]; for (i = n - 1; i >= 0; i--) sa[--c[x[y[i]]]] = y[i]; swap(x, y); p = 1; x[sa[0]] = 0; for (i = 1; i < n; i++) x[sa[i]] = (y[sa[i - 1]] == y[sa[i]] && y[sa[i - 1] + k] == y[sa[i] + k]) ? p - 1 : p++; if (p >= n) break; m = p; } n--; } void getHeight() { int i, j, k = 0; for (i = 1; i <= n; i++) rank[sa[i]] = i; for (i = 0; i < n; i++) { if (k) k--; int j = sa[rank[i] - 1]; while (s[i + k] == s[j + k]) k++; height[rank[i]] = k; } } void initRMQ() { for (int i = 1; i <= n; i++) best[i][0] = height[i]; for (int j = 1; (1<<j) <= n; j++) for (int i = 1; i + (1<<j) - 1 <= n; i++) best[i][j] = min(best[i][j - 1], best[i + (1<<(j - 1))][j - 1]); } int lcp(int L, int R) { L = rank[L]; R = rank[R]; if (L > R) swap(L, R); L++; int k = 0; while ((1<<(k + 1)) <= R - L + 1) k++; return min(best[L][k], best[R - (1<<k) + 1][k]); } void init() { n = 0; scanf("%d%s", &g, str); len = strlen(str); for (int i = 0; i < len; i++) s[n++] = str[i] - 'a' + 1; s[n++] = 27; for (int i = len - 1; i >= 0; i--) s[n++] = str[i] - 'a' + 1; s[n] = 0; } ll solve() { init(); build_sa(28); getHeight(); initRMQ(); ll ans = 0; for (int d = 1; d < len / 2; d++) { for (int j = 0; j < len; j += d) { int l = j, r = j + d + g, sum = 0; if (r < len) sum += min(lcp(l, r), d); if (l >= 1) sum += min(lcp(n - l, n - r), d - 1); ans += max(0, sum - d + 1); } } return ans; } } gao; int t; int main() { int cas = 0; scanf("%d", &t); while(t--) { printf("Case %d: %lld\n", ++cas, gao.solve()); } return 0; }
UVA 10829 - L-Gap Substrings(后缀数组)
标签:style http color os io for ar 代码 amp
原文地址:http://blog.csdn.net/accelerator_/article/details/38780843