复杂度按理能过啊/yiw

也不知道细节有什么问题/kel

#include<bits/stdc++.h>
#define int long long
using namespace std;
int n, m, a[500005], b[500005], pd[1000005], x, y;
int S[9000005], top;
unordered_map<int, int> f, forbid;
bool check(int u, int v){
	if (v - u > 1000000)
		return 1;
	else
		return pd[v - u];
}
void erase(int x){
	forbid[x] = 1;
}
void insert(int x){
	if (forbid[x])
		return;
	S[++top] = x;
}
signed main(){
	ios::sync_with_stdio(false);
	cin.tie(0);cout.tie(0);
	cin >> n >> m >> x >> y;
	for (int i = 1; i <= m; i++){
		cin >> a[i] >> b[i];
		if (b[i] - a[i] + 1 >= y){
			cout << "No";
			return 0;
		}
	}
	if (x == y){
		if ((n - 1) % x != 0)
		for (int i = 1; i <= m; i++){
			for (int j = a[i]; j <= b[i]; j++){
				if ((j - 1) % x == 0){
					cout << "No";
					return 0;
				}
			}
		}
		cout << "Yes";
		return 0;
	}
	pd[0] = 1;
	for (int i = 0; i <= 1000000; i++){
		if (!pd[i])
			continue;
		for (int j = x; j <= y; j++)
			pd[i + j] = 1;
	}
	for (int i = 1; i <= m; i++){
		for (int j = a[i]; j <= b[i]; j++)
			erase(j);
	}
	insert(1);
	insert(n);
	for (int i = 1; i <= m; i++){
		for (int j = a[i] - 210; j < a[i]; j++)
			insert(j);
		for (int j = b[i] + 1; j <= b[i] + 210; j++)
			insert(j);
	}
	sort(S + 1, S + 1 + top);
	top = unique(S + 1, S + 1 + top) - S - 1;
	f[1] = 1;
	for (int i = 1; i <= top; i++){
		if (f[i] == 0)
			continue;
		for (int j = 1; j <= min(top, j + 420); j++)
			if (check(i, j))
				f[j] = 1;
	}
	if (f[n])
		cout << "Yes";
	else
		cout << "No";
	return 0;
}