_bzoj1014 [JSOI2008]火星人prefix【Splay】

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

天，写kth()时，把判断条件k <= siz[ch[x][0]]错写成了k <= ch[x][0]，RE不停，还爆掉了几个小时，以后写数据结构题一定要头脑清晰啊！

#include <cstdio>
#include <cstring>

const int maxn = 300005, base = 131;

int fa[maxn], ch[maxn][2], key[maxn], siz[maxn], root, cnt;
unsigned long long hash[maxn], poww[maxn];
int n, m, t1, t2, stk[maxn], top;
char s[maxn], opr, t3;

inline void pushup(int x) {
	hash[x] = hash[ch[x][0]] * (poww[siz[ch[x][1]] + 1]) + key[x] * poww[siz[ch[x][1]]] + hash[ch[x][1]];
	siz[x] = siz[ch[x][0]] + siz[ch[x][1]] + 1;
}
inline void rotate(int x) {
	int y = fa[x];
	if (y == ch[fa[y]][0]) {
		ch[fa[y]][0] = x;
	}
	else {
		ch[fa[y]][1] = x;
	}
	fa[x] = fa[y];
	int dir = x == ch[y][1];
	ch[y][dir] = ch[x][dir ^ 1];
	fa[ch[x][dir ^ 1]] = y;
	ch[x][dir ^ 1] = y;
	fa[y] = x;
	pushup(y);
	pushup(x);
}
inline void splay(int x, int rt) {
	int p;
	while (fa[x] != rt) {
		p = fa[x];
		if (fa[p] == rt) {
			rotate(x);
		}
		else {
			if ((p == ch[fa[p]][1]) ^ (x == ch[p][1])) {
				rotate(x);
			}
			else {
				rotate(p);
			}
			rotate(x);
		}
	}
	if (!rt) {
		root = x;
	}
}
int make_tree(int left, int right) {
	if (left > right) {
		return 0;
	}
	int rt = (left + right) >> 1;
	key[rt] = s[rt];
	ch[rt][0] = make_tree(left, rt - 1);
	fa[ch[rt][0]] = rt;
	ch[rt][1] = make_tree(rt + 1, right);
	fa[ch[rt][1]] = rt;
	pushup(rt);
	return rt;
}
inline int kth(int k) {
	int x = root;
	while (k != siz[ch[x][0]] + 1) {
		if (k <= siz[ch[x][0]]) {
			x = ch[x][0];
		}
		else {
			k -= siz[ch[x][0]] + 1;
			x = ch[x][1];
		}
	}
	return x;
}
inline void modify(int root1, int root2) {
	root1 = kth(root1);
	root2 = kth(root2);
	splay(root1, 0);
	splay(root2, root1);
}
inline void ist(int pos, int _key) {
	modify(pos, pos + 1);
	++cnt;
	hash[cnt] = key[cnt] = _key;
	siz[cnt] = 1;
	ch[ch[root][1]][0] = cnt;
	fa[cnt] = ch[root][1];
	pushup(ch[root][1]);
	pushup(root);
}
/*void ist(int x, int k, int _key) {
	if (k == siz[ch[x][0]] + 1) {
		if (ch[x][1]) {
			top = 0;
			int i;
			for (i = ch[x][1]; ch[i][0]; i = ch[i][0]) {
				stk[top++] = i;
			}
			++cnt;
			ch[i][0] = cnt;
			fa[cnt] = i;
			key[cnt] = _key;
			siz[cnt] = 1;
			pushup(i);
			for (i = top - 1; ~i; --i) {
				pushup(stk[i]);
			}
		}
		else {
			++cnt;
			ch[x][1] = cnt;
			fa[cnt] = x;
			key[cnt] = _key;
		}
		pushup(x);
		splay(cnt, 0);
		return;
	}
	if (k <= siz[ch[x][0]]) {
		ist(ch[x][0], k, _key);
	}
	else {
		ist(ch[x][1], k - siz[ch[x][0]] - 1, _key);
	}
}*/
void upd(int x, int k, int _key) {
	if (k == siz[ch[x][0]] + 1) {
		key[x] = _key;
		pushup(x);
		return;
	}
	if (k <= siz[ch[x][0]]) {
		upd(ch[x][0], k, _key);
	}
	else {
		upd(ch[x][1], k - siz[ch[x][0]] - 1, _key);
	}
	pushup(x);
}
unsigned long long gethash(int start, int end) {
	modify(start - 1, end + 1);
	return hash[ch[ch[root][1]][0]];
}

int main(void) {
	//freopen("in.txt", "r", stdin);
	//freopen("out.txt", "w", stdout);
	scanf("%s", s + 2);
	n = strlen(s + 2);
	s[1] = s[n + 2] = '$';
	n += 2;
	cnt = n;
	poww[0] = 1;
	for (int i = 1; i < maxn; ++i) {
		poww[i] = poww[i - 1] * base;
	}
	root = make_tree(1, n);
	scanf("%d", &m);
	int left, right, mid;
	while (m--) {
		while ((opr = getchar()) < 'A');
		scanf("%d", &t1);
		++t1;
		if (opr == 'I') {
			while ((t3 = getchar()) < 'a');
			ist(t1, t3);
			++n;
		}
		else if (opr == 'R') {
			while ((t3 = getchar()) < 'a');
			upd(root, t1, t3);
		}
		else {
			scanf("%d", &t2);
			++t2;
			left = 0;
			right = n - (t1 > t2? t1: t2);
			while (left != right) {
				mid = (left + right + 1) >> 1;
				if (gethash(t1, t1 + mid - 1) == gethash(t2, t2 + mid - 1)) {
					left = mid;
				}
				else {
					right = mid - 1;
				}
			}
			printf("%d
", left);
		}
	}
	return 0;
}