Codeforces School Team Contest #2 B. Cola
DPにするまでもない。
#include <iostream> using namespace std; int main() { int n, a, b, c; cin >> n >> a >> b >> c; int r = 0; for ( int i=0; i<=a; i+=2 ) for ( int j=0; j<=c; j++ ) { int k = n - i/2 - j*2; if ( 0 <= k && k <= b ) r++; } cout << r << endl; }