Algorithm
As you very well know, this year's funkiest numbers are so called triangular numbers (that is, integers that are representable as 
, where k is some positive integer), and the coolest numbers are those that are representable as a sum of two triangular numbers.
A well-known hipster Andrew adores everything funky and cool but unfortunately, he isn't good at maths. Given number n, help him define whether this number can be represented by a sum of two triangular numbers (not necessarily different)!
The first input line contains an integer n (1 ≤ n ≤ 109).
Print "YES" (without the quotes), if n can be represented as a sum of two triangular numbers, otherwise print "NO" (without the quotes).
256
YES
512
NO
In the first sample number 
.
In the second sample number 512 can not be represented as a sum of two triangular numbers.
Code Examples
#1 Code Example with C++ Programming
Code -
C++ Programming
#include <bits/stdc++.h>
using namespace std;
int const N = 1e5 + 1;
int n;
set<long long> st;
int main() {
scanf("%d", &n);
for(int i = 1; i < N; ++i)
st.insert(1ll * i * (i + 1) / 2);
for(set<long long>::iterator it = st.begin(); it != st.end(); ++it) {
if(n - (*it)> 0 && st.count(n - (*it))) {
puts("YES");
return 0;
}
}
puts("NO");
return 0;
}Input
Output
Demonstration
Codeforcess Solution Funky Numbers, A. Funky Numbers ,C,C++, Java, Js and Python ,Funky Numbers,Codeforcess Solution