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| #include <cstdio>
#include <algorithm>
const int maxn = 100000 + 5;
const int inf = 1 << 30;
int a[maxn];
struct Splay{
int f[maxn], ch[maxn][2], size[maxn], rev[maxn] = {0}, key[maxn], root, sz;
Splay(){
root = sz = size[0] = rev[0] = f[0] = 0; key[0] = inf;
}
int get(int x){return ch[f[x]][1] == x;}
void pushup(int x){
size[x] = size[ch[x][0]] + size[ch[x][1]] + 1;
}
void pushdown(int x){
if (!rev[x]) return;
std::swap(ch[x][0], ch[x][1]);
rev[ch[x][0]] ^= 1; rev[ch[x][1]] ^= 1; rev[x] = 0;
}
int build(int l, int r, int rt){
if (l > r) return 0;
int m = (l + r) >> 1, tot = ++sz;
key[tot] = a[m]; f[tot] = rt; rev[tot] = 0;
ch[tot][0] = build(l, m - 1, tot);
ch[tot][1] = build(m + 1, r, tot);
pushup(tot);
return tot;
}
void rot(int x){
int old = f[x], oldf = f[old], tp = get(x);
pushdown(old); pushdown(x);
ch[old][tp] = ch[x][tp ^ 1]; f[ch[old][tp]] = old;
ch[x][tp ^ 1] = old; f[old] = x;
f[x] = oldf;
if (oldf) ch[oldf][ch[oldf][1] == old] = x;
pushup(old); pushup(x);
}
void splay(int x, int tar){
for (int fa; (fa = f[x]) != tar; rot(x))
if (f[fa] != tar)
rot(get(fa) == get(x) ? fa : x);
if (!tar) root = x;
}
int find(int k){
int tot = root;
while (1){
pushdown(tot);
if (k <= size[ch[tot][0]]) tot = ch[tot][0];
else {
k -= size[ch[tot][0]] + 1;
if (!k) return tot;
tot = ch[tot][1];
}
}
}
void reverse(int l, int r){
int a = find(l), b = find(r + 2);
splay(a, 0); splay(b, a);
rev[ch[b][0]] ^= 1;
}
void print(int p){
pushdown(p);
if (ch[p][0]) print(ch[p][0]);
if (key[p] != inf) printf("%d ", key[p]);
if (ch[p][1]) print(ch[p][1]);
}
}f;
int n, m;
int main(){
scanf("%d%d", &n, &m);
for (int i = 1; i <= n; i++) a[i + 1] = i;
a[1] = inf; a[n + 2] = inf;
f.root = f.build(1, n + 2, 0);
while (m--){
int l, r; scanf("%d%d", &l, &r);
f.reverse(l, r);
}
f.print(f.root);
return 0;
}
|