【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;
}