An integer sequence is called beautiful if the difference between any two consecutive numbers is equal to $1$. More formally, a sequence $s_1, s_2, \ldots, s_{n}$ is beautiful if $|s_i – s_{i+1}| = 1$ for all $1 \leq i \leq n – 1$.
Trans has $a$ numbers $0$, $b$ numbers $1$, $c$ numbers $2$ and $d$ numbers $3$. He wants to construct a beautiful sequence using all of these $a + b + c + d$ numbers.
However, it turns out to be a non-trivial task, and Trans was not able to do it. Could you please help Trans?Input
The only input line contains four non-negative integers $a$, $b$, $c$ and $d$ ($0 < a+b+c+d \leq 10^5$).Output
If it is impossible to construct a beautiful sequence satisfying the above constraints, print “NO” (without quotes) in one line.
Otherwise, print “YES” (without quotes) in the first line. Then in the second line print $a + b + c + d$ integers, separated by spaces — a beautiful sequence. There should be $a$ numbers equal to $0$, $b$ numbers equal to $1$, $c$ numbers equal to $2$ and $d$ numbers equal to $3$.
If there are multiple answers, you can print any of them.Examplesinput
2 2 2 1
output
YES 0 1 0 1 2 3 2
input
1 2 3 4
output
NO
input
2 2 2 3
output
NO
Note
In the first test, it is easy to see, that the sequence is beautiful because the difference between any two consecutive numbers is equal to $1$. Also, there are exactly two numbers, equal to $0$, $1$, $2$ and exactly one number, equal to $3$.
It can be proved, that it is impossible to construct beautiful sequences in the second and third tests.
Solution:
#include <bits/stdc++.h>
using namespace std;
int main() {
ios::sync_with_stdio(false);
cin.tie(0);
vector<int> a(4);
for (int i = 0; i < 4; i++) {
cin >> a[i];
}
for (int rot = 0; rot < 2; rot++) {
vector<int> backup_a = a;
int even = a[0] + a[2];
int odd = a[1] + a[3];
if (odd == even || odd == even - 1) {
vector<int> b(a[0] + a[1] + a[2] + a[3], - 1);
for (int i = 0; i < (int) b.size(); i += 2) {
if (a[0] > 0) {
b[i] = 0;
--a[0];
} else {
b[i] = 2;
--a[2];
}
}
for (int i = 1; i < (int) b.size(); i += 2) {
if (a[1] > 0) {
b[i] = 1;
--a[1];
} else {
b[i] = 3;
--a[3];
}
}
bool ok = true;
for (int i = 0; i < (int) b.size() - 1; i++) {
ok &= (abs(b[i] - b[i + 1]) == 1);
}
if (ok) {
cout << "YES" << '\n';
for (int i = 0; i < (int) b.size(); i++) {
if (i > 0) {
cout << " ";
}
cout << (rot == 0 ? b[i] : 3 - b[i]);
}
cout << '\n';
return 0;
}
}
a = backup_a;
reverse(a.begin(), a.end());
}
cout << "NO" << '\n';
return 0;
}