求助Treap，样例过了，全哇了

具体方法：使用 Treap 建树，将树解剖出所求区域 [k1-k2]，将所求区域的根节点打上标记，最后中序遍历输出，若遇到被标记的点，则将标记下传，并交换左右字数

#include <bits/stdc++.h>
using namespace std;
const int N = 1e5+5;
const int INF = 0x7fffffff;

struct node {
    int val;
    bool reversed;
    int count;
    int pr;
    int left, right;
}tre[N];

int counter = 0;
int root = -1;

int count(int u){return (u == -1)? 0 : tre[u].count;}

void pushup(int u){
    tre[u].count = count(tre[u].left) + count(tre[u].right) + 1;
}

void pushdown(int u) {
    if(tre[u].reversed){
        if(tre[u].left != -1) tre[tre[u].left].reversed = !tre[tre[u].left].reversed;
        if (tre[u].right != -1) tre[tre[u].right].reversed = !tre[tre[u].right].reversed;
        swap(tre[u].left, tre[u].right);
        tre[u].reversed = false;
    }
}

void replace_by_child(int c,int u,int f) {
    if (f == -1) root = c;
    else if (tre[f].left == u) tre[f].left = c;
    else if (tre[f].right == u) tre[f].right = c;
}

void right_rotate(int u,int f) {
    int c = tre[u].left;
    tre[u].left = tre[c].right;
    tre[c].right = u;
    pushup(u);
    pushup(c);
    replace_by_child(c,u,f);
}

void left_rotate(int u, int f) {
    int c = tre[u].right;
    tre[u].right = tre[c].left;
    tre[c].left = u;
    pushup(u);
    pushup(c);
    replace_by_child(c,u,f);
}

void make_new(int &u,int val,int f,bool is_left){
    u = counter++;
    tre[u].val = val;
    tre[u].reversed = false;
    tre[u].pr = rand();
    tre[u].count = 1;
    tre[u].left = -1;
    tre[u].right = -1;
    if (f == -1) root = u;
    else if (is_left) tre[f].left = u;
    else tre[f].right = u;
}

void insert(int k, int val, int u, int f = -1, bool is_left = true){
    if (u == -1) make_new(u,val,f,is_left);

    else if (k <= count(tre[u].left) + 1) {
        pushdown(u);
        insert(k, val, tre[u].left, u, true);
        pushup(u);
        if (tre[tre[u].left].pr > tre[u].pr) right_rotate(u, f);
    }
    else{
        pushdown(u);
        insert(k - count(tre[u].left) - 1, val, tre[u].right, u, false);
        pushup(u);
        if (tre[tre[u].right].pr > tre[u].pr) left_rotate(u, f);
    }
}

pair<int, int> split(int k, int u) {
    if (u == -1) return make_pair(-1, -1);
    else if (k < count(tre[u].left) + 1) {
        pushdown(u);
        pair<int, int> p = split(k, tre[u].left);
        tre[u].left = p.second;
        pushup(u);
        return make_pair(p.first, u);
    }
    else {
        pushdown(u);
        pair<int, int> p = split(k - count(tre[u].left) - 1, tre[u].right);
        tre[u].right = p.first;
        pushup(u);
        return make_pair(u, p.second);
    }
}

void dfs(int u) {
    if(u == -1) return;
    else{
        pushdown(u);
        dfs(tre[u].left);
        printf("%d ",tre[u].val);
        dfs(tre[u].right);
    }
}

int merge(int u, int v) {
    if (u == -1) return v;
    else if (v == -1) return u;
    else if (tre[u].pr > tre[v].pr) {
        pushdown(u);
        tre[u].right = merge(tre[u].right, v);
        pushup(u);
        return u;
    }
    else{
        pushdown(v);
        tre[v].left = merge(u, tre[v].left);
        pushup(v);
        return v;
    }
}

int m,n;

int main(){
//  freopen("P3391_1.in","r",stdin);

    srand(114514);
    scanf("%d %d",&n,&m);
    for(int i=1;i<=n;i++) insert(i,i,root);

    //dfs(root);
    //printf("\n");

    for (int i=1;i<=m; ++i) {
        int k1, k2;
        scanf("%d%d", &k1, &k2);
        if(k1 > k2) swap(k1,k2);

        pair<int,int> p2 = split(k2, root);
        pair<int,int> p1 = split(k1 - 1, p2.first);
        int left = p1.first;
        int right = p2.second;
        int n = p1.second;
        tre[n].reversed = !tre[n].reversed;
        left = merge(left, n);
        root = merge(left, right);
        //dfs(root);
    //  printf("\n");
    }
    dfs(root);
    return 0;
}