传送门:DISUBSTR
题意:给定一个字符串,求不相同的子串。
分析:对于每个sa[i]贡献n-a[i]个后缀,然后减去a[i]与a[i-1]的公共前缀height[i],则每个a[i]贡献n-sa[i]-height[i]个不同子串。
#include <iostream> #include <cstdio> #include <cstring> #include <algorithm> #include <queue> using namespace std; const int maxn = 1010; int sa[maxn]; int t1[maxn], t2[maxn], c[maxn]; int rank[maxn], height[maxn]; int s[maxn]; char str[maxn]; void build_sa(int s[], int n, int m) { int i, j, p, *x = t1, *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 (j = 1; j <= n; j <<= 1) { p = 0; for (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 < m; i++) c[i] = 0; for (i = 0; i < n; i++) c[x[y[i]]]++; for (i = 1; 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]+j] == y[sa[i]+j] ? p-1 : p++; if (p >= n) break; m = p; } } void getHeight(int s[],int n) { int i, j, k = 0; for (i = 0; i <= n; i++) rank[sa[i]] = i; for (i = 0; i < n; i++) { if (k) k--; j = sa[rank[i]-1]; while (s[i+k] == s[j+k]) k++; height[rank[i]]=k; } } int main() { int T; scanf("%d", &T); while (T--) { scanf("%s", str); int n = strlen(str); for (int i = 0; i <= n; i++) s[i] = str[i]; build_sa(s, n+1, 128); getHeight(s, n); int ans = 0; for (int i = 1; i <= n; i++) ans += n - sa[i] - height[i]; printf("%d ", ans); } return 0; }