【BZOJ1014】[JSOI2008]火星人prefix【Splay】【Hash】

http://www.lydsy.com/JudgeOnline/problem.php?id=1014

学习一发树上Hash。

10s卡时过了。

/* Footprints In The Blood Soaked Snow */
#include <cstdio>
#include <cstring>
#include <algorithm>

using namespace std;

typedef long long LL;

const int maxn = 100005, base = 9875321;

int n, num[maxn], P[maxn];
int son[maxn][2], val[maxn], hash[maxn], pre[maxn], size[maxn];
int tot1, root;

inline void newnode(int &x, int c, int f) {
	x = ++tot1;
	son[x][0] = son[x][1] = 0;
	val[x] = hash[x] = c;
	pre[x] = f;
	size[x] = 1;
}

inline void pushup(int x) {
	int l = son[x][0], r = son[x][1];
	size[x] = size[l] + 1 + size[r];
	hash[x] = (hash[l] + (LL)P[size[l]] * val[x] % base + (LL)P[size[l] + 1] * hash[r] % base) % base;
}

inline void build(int &x, int l, int r, int f) {
	if(l > r) return;
	int mid = l + r >> 1;
	newnode(x, num[mid], f);
	build(son[x][0], l, mid - 1, x); build(son[x][1], mid + 1, r, x);
	pushup(x);
}

inline void init() {
	root = tot1 = 0;
	son[0][0] = son[0][1] = val[0] = hash[0] = pre[0] = size[0] = 0;
	newnode(root, 0, 0);
	newnode(son[root][1], 0, root);
	build(son[son[root][1]][0], 1, n, son[root][1]);
	pushup(son[root][1]); pushup(root);
}

inline void rotate(int x) {
	int y = pre[x], z = pre[y], type = son[y][1] == x;
	pre[son[y][type] = son[x][!type]] = y;
	pre[x] = z;
	if(z) son[z][son[z][1] == y] = x;
	pre[son[x][!type] = y] = x;
	pushup(y); pushup(x);
}

inline void splay(int x, int goal) {
	while(pre[x] != goal) {
		int y = pre[x], z = pre[y];
		if(z == goal) rotate(x);
		else if(son[z][1] == y ^ son[y][1] == x) rotate(x), rotate(x);
		else rotate(y), rotate(x);
	}
	if(goal == 0) root = x;
}

inline int find(int k) {
	int x = root;
	while(k != size[son[x][0]] + 1)
		if(k <= size[son[x][0]]) x = son[x][0];
		else k -= size[son[x][0]] + 1, x = son[x][1];
	return x;
}

inline int gethash(int x, int y) {
	x = find(x); y = find(y + 2);
	splay(x, 0); splay(y, root);
	return hash[son[y][0]];
}

inline int query(int x, int y) {
	int l = 1, r = tot1 - y - 1;
	while(l <= r) {
		int mid = l + r >> 1;
		if(gethash(x, x + mid - 1) == gethash(y, y + mid - 1)) l = mid + 1;
		else r = mid - 1;
	}
	return r;
}

inline void replace(int pos, int c) {
	int x = find(pos + 1);
	splay(x, 0);
	val[x] = c;
	pushup(x);
}

inline void insert(int pos, int c) {
	int x = find(pos + 1), y = find(pos + 2);
	splay(x, 0); splay(y, root);
	newnode(son[y][0], c, y);
	pushup(y); pushup(x);
}

char str[maxn];

int main() {
	scanf("%s", str + 1); n = strlen(str + 1);
	for(int i = 1; i <= n; i++) num[i] = str[i] - 'a' + 1;

	P[0] = 1;
	for(int i = 1; i < maxn; i++) P[i] = P[i - 1] * 27, P[i] %= base;
	init();

	int m; scanf("%d", &m);
	while(m--) {
		char ch = getchar(); for(; ch != 'Q' && ch != 'R' && ch != 'I'; ch = getchar());
		if(ch == 'Q') {
			int x, y; scanf("%d%d", &x, &y); if(x > y) swap(x, y);
			printf("%d\n", query(x, y));
		}
		else if(ch == 'R') {
			int x; scanf("%d%s", &x, str);
			replace(x, str[0] - 'a' + 1);
		}
		else if(ch == 'I') {
			int x; scanf("%d%s", &x, str);
			insert(x, str[0] - 'a' + 1);
		}
	}
	return 0;
}