Hdu 1754 I Hate It (splay tree extension tree)

# Include <stdio. h> # include <string. h ># include <algorithm> using namespace std; const int maxn = 222222; int son [2] [maxn], col [maxn], fa [maxn], size [maxn], val [maxn]; int tot; int num [maxn]; void new_node () {size [tot] = 1; fa [tot] = son [0] [tot] = son [1] [tot] =-1; val [tot] = col [tot] = 0; tot ++;} void update (int rt) {size [rt] = 1; col [rt] = val [rt]; if (son [0] [rt]! =-1) size [rt] + = size [son [0] [rt], col [rt] = max (col [rt], col [son [0] [rt]); if (son [1] [rt]! =-1) size [rt] + = size [son [1] [rt], col [rt] = max (col [rt], col [son [1] [rt]);} int build (int l, int r) {if (l> r) return-1; int mid = (l + r)> 1; new_node (); int temp = tot-1; val [temp] = num [mid]; son [0] [temp] = build (l, mid-1); if (son [0] [temp]! =-1) fa [son [0] [temp] = temp; son [1] [temp] = build (mid + 1, r ); if (son [1] [temp]! =-1) fa [son [1] [temp] = temp; update (temp); return temp;} void rot (int rt, int c) {int y = fa [rt], z = fa [y]; son [! C] [y] = son [c] [rt]; if (son [c] [rt]! =-1) fa [son [c] [rt] = y; fa [rt] = z; if (z! =-1) {if (y = son [0] [z]) son [0] [z] = rt; else son [1] [z] = rt ;} son [c] [rt] = y, fa [y] = rt; update (y);} void splay (int rt, int to) {while (fa [rt]! = To) {if (fa [fa [rt] = to) {if (rt = son [0] [fa [rt]) rot (rt, 1); else rot (rt, 0);} else {int y = fa [rt], z = fa [y]; if (rt = son [0] [y]) {if (y = son [0] [z]) rot (y, 1), rot (rt, 1); else rot (rt, 1), rot (rt, 0);} else {if (y = son [1] [z]) rot (y, 0), rot (rt, 0); else rot (rt, 0), rot (rt, 1) ;}} update (rt ); /* why do I only need to update the rt node at the end? In the course of rotation, fa [rt] Always rotates under rt, So we constantly update fa [rt] without updating rt all the time, update rt after splay. */} int find (int rt, int key) {int cnt = 0; if (son [0] [rt]! =-1) cnt = size [son [0] [rt]; if (cnt + 1 = key) return rt; if (cnt> = key) return find (son [0] [rt], key); return find (son [1] [rt], key-cnt-1);} int main () {int n, m, I, j, k, a, B; char op [11]; while (scanf ("% d", & n, & m )! = EOF) {for (I = 1; I <= n; I ++) scanf ("% d", & num [I]); tot = 0; int root = build (0, n + 1), temp; while (m --) {scanf ("% s % d", op, & a, & B ); a ++, B ++; // when creating a table, 0 is also created, but 0 is not in the original array, one if (op [0] = 'U') {temp = find (root, a); splay (temp,-1); root = temp; val [root] = B-1; // update (root); // Why not update rt here? Because the size value will not change, but the val value has been updated, and for the col value, the next time it is splay, will certainly be updated} else {temp = find (root, a-1); splay (temp,-1); root = temp; temp = find (root, B + 1); splay (temp, root); printf ("% d \ n", col [son [0] [temp]) ;}}}