BZOJ 4199: [Noi2015]品酒大会( 后缀数组 + 并查集 )

求出后缀数组后, 对height排序, 从大到小来处理(r相似必定是0~r-1相似), 并查集维护. 复杂度O(NlogN + Nalpha(N)) 

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#include<cstdio>

#include<cstring>

#include<algorithm>

 

using namespace std;

 

typedef long long ll;

 

const ll INF = -1LL << 60;

const int maxn = 300009;

 

char S[maxn];

int w[maxn], N;

int cnt[maxn], Sa[maxn], Rank[maxn], Height[maxn];

int mx[maxn], mn[maxn], fa[maxn], sz[maxn], r[maxn];

ll ans[maxn], tot[maxn];

 

void Init() {

scanf("%d%s", &N, S);

for(int i = 0; i < N; i++) scanf("%d", w + i);

S[N++] = '$';

}

 

void Build() {

int m = 255, *x = Height, *y = Rank;

for(int i = 0; i < m; i++) cnt[i] = 0;

for(int i = 0; i < N; i++) cnt[x[i] = S[i]]++;

for(int i = 1; i < m; i++) cnt[i] += cnt[i - 1];

for(int i = N; i--; ) Sa[--cnt[x[i]]] = i;

for(int k = 1, p = 0; k <= N; k <<= 1, p = 0) {

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

for(int i = 0; i < N; i++)

if(Sa[i] >= k) y[p++] = Sa[i] - k;

for(int i = 0; i < m; i++) cnt[i] = 0;

for(int i = 0; i < N; i++) cnt[x[y[i]]]++;

for(int i = 1; i < m; i++) cnt[i] += cnt[i - 1];

for(int i = N; i--; ) Sa[--cnt[x[y[i]]]] = y[i];

swap(x, y), x[Sa[0]] = 0, p = 1;

for(int i = 1; i < N; i++) {

if(y[Sa[i]] != y[Sa[i - 1]] || y[Sa[i] + k] != y[Sa[i - 1] + k]) p++;

x[Sa[i]] = p - 1;

}

if((m = p) >= N) break;

}

for(int i = 0; i < N; i++) Rank[Sa[i]] = i;

Height[0] = 0;

for(int i = 0, h = 0; i < N; i++) if(Rank[i]) {

if(h) h--;

while(S[i + h] == S[Sa[Rank[i] - 1] + h]) h++;

Height[Rank[i]] = h;

}

}

 

int Find(int x) {

return x == fa[x] ? x : fa[x] = Find(fa[x]);

}

 

bool Cmp(const int &l, const int &r) {

return Height[l] > Height[r];

}

 

inline void Max(ll &x, ll t) {

if(t > x) x = t;

}

inline void Max(int &x, int t) {

if(t > x) x = t;

}

inline void Min(int &x, int t) {

if(t < x) x = t;

}

 

void Work() {

for(int i = 0; i < N; i++) {

sz[i] = 1;

r[i] = fa[i] = i;

mx[i] = mn[i] = w[i];

tot[i] = 0;

ans[i] = INF;

}

sort(r, r + N, Cmp);

for(int i = 0; i < N; i++) if(r[i] > 1) {

int u = Find(Sa[r[i]]), v = Find(Sa[r[i] - 1]);

if(u == v) continue;

tot[Height[r[i]]] += ll(sz[u]) * sz[v];

Max(ans[Height[r[i]]], max(ll(mx[u]) * mx[v], ll(mn[u]) * mn[v]));

fa[u] = v, sz[v] += sz[u];

Max(mx[v], mx[u]);

Min(mn[v], mn[u]);

}

for(int i = Height[r[0]]; i--; )

tot[i] += tot[i + 1], Max(ans[i], ans[i + 1]);

for(int i = 0; i + 1 < N; i++)

printf("%lld %lld\n", tot[i], ans[i] != INF ? ans[i] : 0);

}

 

int main() {

Init();

Build();

Work();

return 0;

}

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