刚开始学spaly，所以一上来不会打标记，后来想了想splay的区间操作和线段树其实基本一样。
lazy标记的下推注意一下， update时如果直接进行splay操作的话会因lazy标记没有下推而出错，正确做法是在splay操作前先进行一个区间第k大查询操作（因为区间反转破坏了二叉搜索树的性质，所以我们只能进行区间第k大的查询来辅助下推）
#include <cstdio>
#include <cstring>
#include <iostream>
#include <algorithm>
using namespace std;
const int maxn = 1e5 + 10;
int n, m;
struct Splay {
int sz, root, fa[maxn], ch[maxn][2], key[maxn], size[maxn], lazy[maxn];
void newnode(int x, int f, int v) { fa[x] = f, key[x] = v; size[x] = 1; }
void pushup(int x) {
if (!x) return;
size[x] = size[ch[x][0]] + size[ch[x][1]] + 1;
}
void pushdown(int x) {
if (!x || !lazy[x]) return;
lazy[ch[x][0]] ^= 1;
lazy[ch[x][1]] ^= 1;
swap(ch[ch[x][0]][0], ch[ch[x][0]][1]);
swap(ch[ch[x][1]][0], ch[ch[x][1]][1]);
lazy[x] = 0;
}
int build(int l, int r, int f) {
if (l > r) return 0;
int mid = (l + r) >> 1;
int x = ++sz;
newnode(x, f, mid);
ch[x][0] = build(l, mid-1, x);
ch[x][1] = build(mid+1, r, x);
pushup(x);
return x;
}
int pos(int x) {
return ch[fa[x]][1] == x;
}
void rotate(int x) {
int y = fa[x], z = fa[y], posx = pos(x), posy = pos(y);
ch[y][posx] = ch[x][posx^1]; fa[ch[y][posx]] = y;
ch[x][posx^1] = y; fa[y] = x;
fa[x] = z; if (z) ch[z][posy] = x;
pushup(y); pushup(x);
}
void splay(int x, int y) {
for (int f; (f=fa[x]) != y; rotate(x)) {
if (fa[f] != y) rotate(pos(x) == pos(f)?f:x);
}
if (y == 0) root = x;
}
int kth(int x, int k) {
pushdown(x);
if (size[ch[x][0]]+1 == k) return x;
if (size[ch[x][0]]+1 > k) return kth(ch[x][0], k);
else return kth(ch[x][1], k-size[ch[x][0]]-1);
}
void update(int l, int r) {
int x = kth(root, l), y = kth(root, r);
splay(x, 0); splay(y, x);
int z = ch[y][0];
swap(ch[z][0], ch[z][1]);
lazy[z] ^= 1;
}
void query(int x) {
if (!x) return;
pushdown(x);
query(ch[x][0]);
if (1 <= key[x]-1 && key[x]-1 <= n) printf("%d ", key[x]-1);
query(ch[x][1]);
}
}ac;
int main() {
int l, r;
scanf("%d%d", &n, &m);
ac.root = ac.build(1, n+2, 0);
while (m--) {
scanf("%d%d", &l, &r);
l++, r++;
ac.update(l-1, r+1);
}
ac.query(ac.root);
printf("\n");
return 0;
}