using
System;
using
System.Collections.Generic;
class
Gfg {
public
static
bool
findfour(
int
[] arr,
int
n,
int
k)
{
Dictionary<
int
, List<Tuple<
int
,
int
> > > hash
=
new
Dictionary<
int
,
List<Tuple<
int
,
int
> > >();
for
(
int
i = 0; i < n; i++) {
for
(
int
j = i + 1; j < n; j++) {
int
sum = arr[i] + arr[j];
if
(hash.ContainsKey(k - sum)) {
List<Tuple<
int
,
int
> > v
= hash[k - sum];
for
(
int
kk = 0; kk < v.Count; kk++) {
Tuple<
int
,
int
> it = v[kk];
if
(it.Item1 != i && it.Item1 != j
&& it.Item2 != i
&& it.Item2 != j) {
return
true
;
}
}
}
if
(!hash.ContainsKey(sum)) {
hash.Add(sum,
new
List<Tuple<
int
,
int
> >());
}
hash[sum].Add(Tuple.Create(i, j));
}
}
hash.Clear();
return
false
;
}
public
static
void
Main(
string
[] args)
{
int
k = 7;
int
[] arr = { 1, 5, 1, 0, 6, 0 };
int
n = arr.Length;
if
(findfour(arr, n, k)) {
Console.WriteLine(
"YES"
);
}
else
{
Console.WriteLine(
"NO"
);
}
}
}
class
Pair {
public
int
first;
public
int
second;
public
Pair(
int
first,
int
second)
{
this
.first = first;
this
.second = second;
}
}