BZOJ4698: Sdoi2008 Sandy的卡片(字尾陣列 二分)
阿新 • • 發佈:2018-11-28
題意
Sol
不要問我為什麼發兩篇blog,就是為了騙訪問量
字尾陣列的也比較好想,先把所有位置差分,然後在height陣列中二分就行了
資料好水啊
// luogu-judger-enable-o2 #include<bits/stdc++.h> using namespace std; const int MAXN = 2e6 + 10; const int INF = 2333; inline int read() { char c = getchar(); int x = 0, f = 1; while(c < '0' || c > '9') {if(c == '-') f = -1; c = getchar();} while(c >= '0' && c <= '9') x = x * 10 + c - '0', c = getchar(); return x * f; } int T, N, M, a[MAXN], id[MAXN], rak[MAXN], tp[MAXN], tax[MAXN], H[MAXN], vis[MAXN], sa[MAXN], ti, mx; void Qsort() { for(int i = 0; i <= M; i++) tax[i] = 0; for(int i = 1; i <= N; i++) tax[rak[i]]++; for(int i = 1; i <= M; i++) tax[i] += tax[i - 1]; for(int i = N; i >= 1; i--) sa[tax[rak[tp[i]]]--] = tp[i]; } void SuffixSort() { for(int i = 1; i <= N; i++) rak[i] = a[i], tp[i] = i; M = N + INF; Qsort(); for(int w = 1, p = 0; p < N; w <<= 1, M = p) { p = 0; for(int i = 1; i <= w; i++) tp[++p] = N - i + 1; for(int i = 1; i <= N; i++) if(sa[i] > w) tp[++p] = sa[i] - w; Qsort(); swap(rak, tp); rak[sa[1]] = p = 1; for(int i = 2; i <= N; i++) rak[sa[i]] = (tp[sa[i]] == tp[sa[i - 1]] && tp[sa[i] + w] == tp[sa[i - 1] + w]) ? p : ++p; } for(int i = 1, k = 0; i <= N; i++) { if(k) k--; int j = sa[rak[i] - 1]; while(a[i + k] == a[j + k]) k++; H[rak[i]] = k; } } bool check(int len) { ti++; int now = 0; for(int i = 1; i <= N; i++) { if(H[i] < len) {now = 0, ti++; continue;} if(vis[id[sa[i]]] != ti) vis[id[sa[i]]] = ti, now++; if(now == T) return 1; } return 0; } int main() { //freopen("a.in", "r", stdin); T = read(); for(int i = 1; i <= T; i++) { int num = read() - 1, pre = read(); a[++N] = i; id[N] = i; mx = max(mx, num + 1); while(num--) a[++N] = read() - pre + INF, pre = a[N] + pre - INF, id[N] = i; } SuffixSort(); int l = 1, r = mx, ans = 0; while(l <= r) { int mid = l + r >> 1; if(check(mid)) ans = mid, l = mid + 1; else r = mid - 1; } printf("%d", ans + 1); return 0; }