rt，2天了，人已经疯了，救救孩子/kel

// created time : 2022-04-08 19:17:16
// writer : fjy
#include <bits/stdc++.h>
#define _rep(i_,a_,b_) for(int i_ = a_;i_ <= b_;++i_)
typedef long long ll;
int in(void) { int x; scanf("%d",&x); return x; }
ll inl(void) { ll x; scanf("%lld",&x); return x; }
using namespace std;
const int kN = 500500;
int ch[kN][2], fa[kN], ncnt, root, siz[kN]; //Splay 主体
int val[kN], lsum[kN], rsum[kN], sum[kN], dat[kN]; //维护的数据
int rev[kN], tag[kN]; //标记

void pushup(int x) {
	sum[x] = sum[ch[x][0]] + sum[ch[x][1]] + val[x];

	// lsum[x] = max(lsum[ch[x][0]], sum[ch[x][0]] + val[x] + max(lsum[ch[x][1]],0));
	lsum[x] = sum[ch[x][0]] + val[x] + max(lsum[ch[x][1]],0);
	if(ch[x][0]) lsum[x] = max(lsum[x],lsum[ch[x][0]]);

	// rsum[x] = max(rsum[ch[x][1]], sum[ch[x][1]] + val[x] + max(rsum[ch[x][0]],0));
	rsum[x] = sum[ch[x][1]] + val[x] + max(rsum[ch[x][0]],0);
	if(ch[x][1]) rsum[x] = max(rsum[x],rsum[ch[x][1]]);
	
	// dat[x] = max({dat[ch[x][0]], dat[ch[x][1]], max(rsum[ch[x][0]],0) + val[x] + max(lsum[ch[x][1]],0)});
	dat[x] = max(rsum[ch[x][0]],0) + val[x] + max(lsum[ch[x][1]],0);
	if(ch[x][0]) dat[x] = max(dat[x], dat[ch[x][0]]);
	if(ch[x][1]) dat[x] = max(dat[x], dat[ch[x][1]]);
	
	siz[x] = siz[ch[x][0]] + siz[ch[x][1]] + 1;
}

int build(int *a,int l,int r,int f) {
	if(l > r) return 0;
	int id = ++ncnt,mid = (l + r) >> 1;
	val[id] = a[mid], fa[id] = f, rev[id] = 0, tag[id] = INT_MIN;
	ch[id][0] = build(a,l,mid - 1,id);
	ch[id][1] = build(a,mid + 1,r,id);
	pushup(id);
	return id;
}

void pushdown(int x) {
	if(rev[x] != 0) {
		rev[x] = 0;
		swap(ch[x][0],ch[x][1]);
		rev[ch[x][0]] ^= 1;
		rev[ch[x][1]] ^= 1;
		swap(lsum[ch[x][0]],rsum[ch[x][0]]);
		swap(lsum[ch[x][1]],rsum[ch[x][1]]);
	}
	if(tag[x] != INT_MIN) {
#define set_interval(x,to)\
	tag[x] = val[x] = to;\
	lsum[x] = rsum[x] = dat[x] = max(to,to * siz[x]);\
	sum[x] = siz[x] * to;
		if(ch[x][0]) set_interval(ch[x][0],tag[x]);
		if(ch[x][1]) set_interval(ch[x][1],tag[x]);
		tag[x] = INT_MIN;
	} 
}

int get(int x) { return ch[fa[x]][1] == x; }
void rotate(int x) {
	int y = fa[x],z = fa[y],d = get(x);
	ch[y][d] = ch[x][d ^ 1]; fa[ch[x][d ^ 1]] = y;
	ch[z][get(y)] = x; fa[x] = z;
	ch[x][d ^ 1] = y; fa[y] = x;
	pushup(y); pushup(x);
}

void splay(int x,int goal = 0) {
	while(fa[x] != goal) {
		int y = fa[x],z = fa[y];
		if(z != goal) rotate(get(x) == get(y) ? y : x);
		rotate(x);
	}
	if(!goal) root = x;
}

int kth(int k) {
	int cur = root;
	while(true) {
		pushdown(cur);
		if(siz[ch[cur][0]] >= k) cur = ch[cur][0];
		else if(siz[ch[cur][0]] + 1 < k) k -= siz[ch[cur][0]] + 1,cur = ch[cur][1];
		else {
			splay(cur);
			return cur;
		}
	}
}

int a[kN],b[kN];

#define no_tag(node) (rev[node] == 0 && tag[node] == INT_MIN)

inline void insert(int x,int rt) { //在 x 后面插入树 rt
	int a = kth(x + 1),b = kth(x + 2); 
	splay(a); splay(b,a); assert(no_tag(a) && no_tag(b));
	ch[b][0] = rt; fa[rt] = b;
	pushup(b); pushup(a);
}

inline void remove(int x,int tot) { //删除从 x 开始的连续 tot 个数字
	int a = kth(x), b = kth(x + tot + 1);
	splay(a); splay(b,a); assert(no_tag(a) && no_tag(b));
	ch[b][0] = 0;
	pushup(b); pushup(a);
}

inline void make_same(int x,int tot,int y) {
	int a = kth(x), b = kth(x + tot + 1);
	splay(a); splay(b,a); assert(no_tag(a) && no_tag(b));
	set_interval(ch[b][0],y); 
	pushup(b); pushup(a);
} 

inline void reverse(int x,int tot) {
	int a = kth(x), b = kth(x + tot + 1);
	splay(a); splay(b,a); assert(no_tag(a) && no_tag(b));
	rev[ch[b][0]] ^= 1;
	swap(lsum[ch[b][0]],rsum[ch[b][0]]);
	pushup(b); pushup(a);
}

inline int get_sum(int x,int tot) {
	int a = kth(x), b = kth(x + tot + 1);
	splay(a); splay(b,a); assert(no_tag(a) && no_tag(b));
	return sum[ch[b][0]];
}

inline int max_sum(void) {
	return dat[root];
}

void flatten(int rt) {
	if(!rt) return;
	// pushdown(rt);
	printf("%d(",val[rt]);
	flatten(ch[rt][0]);
	printf(",");
	flatten(ch[rt][1]);
	printf(")");
}

char command[150];
int main() {
	// freopen("in.txt","r",stdin);
	int n = in(),m = in();
	_rep(i,1,n) a[i] = in();
	a[0] = -1030, a[n + 1] = -1030;
	root = build(a,0,n + 1,0);
	// flatten(root);
	// puts("");

	_rep(i,1,m) {
		scanf("%s",command);
		if(strcmp(command,"MAX-SUM") == 0) { printf("%d\n",max_sum()); continue; }
		int pos = in(),tot = in();
		if(strcmp(command,"INSERT") == 0) {
			_rep(i,1,tot) b[i] = in();
			insert(pos,build(b,1,tot,0));
		}
		if(strcmp(command,"DELETE") == 0)
			remove(pos,tot);
		if(strcmp(command,"MAKE-SAME") == 0)
			make_same(pos,tot,in());
		if(strcmp(command,"REVERSE") == 0)
			reverse(pos,tot);
		if(strcmp(command,"GET-SUM") == 0)
			printf("%d\n",get_sum(pos,tot));
		// flatten(root); puts("");
		_rep(i,1,ncnt) printf("val[%d] = %d,fa[%d] = %d,ch[%d][0] = %d,ch[%d][1] = %d\n",i,val[i],i,fa[i],i,ch[i][0],i,ch[i][1]);
		puts("-----");
	}

	return 0;
}

错误数据：

5 3
9 1 2 9 0 
MAKE-SAME 1 4 6
DELETE 3 1
MAX-SUM 

正确输出：18