Problem:
Score : 200 points

Problem Statement

You are given two integers K and S.

Three variable X, Y and Z takes integer values satisfying 0≤X,Y,Z≤K.

How many different assignments of values to X, Y and Z are there such that X + Y + Z = S?

Constraints

2≤K≤2500

0≤S≤3K

K and S are integers.

Input

The input is given from Standard Input in the following format:

K S

Output

Print the number of the triples of X, Y and Z that satisfy the condition.

Sample Input 1

2 2

Sample Output 1

6

There are six triples of X, Y and Z that satisfy the condition:

X = 0, Y = 0, Z = 2

X = 0, Y = 2, Z = 0

X = 2, Y = 0, Z = 0

X = 0, Y = 1, Z = 1

X = 1, Y = 0, Z = 1

X = 1, Y = 1, Z = 0

Sample Input 2

5 15

Sample Output 2

1

The maximum value of X + Y + Z is 15, achieved by one triple of X, Y and Z.

Solution in C (GCC 5.4.1) (judge verdict: Time Limit Exceeded)

#include <stdio.h>

int min(int a, int b){
  if( a > b)return b;
  return a;
}

int zero(int a){
  if( a < 0)return 0;
  return a;
}
int main(int argc, char const *argv[]) {
  int k,s;
  int x,y,z;
  int i,j,l;
  int count=0;
  scanf("%d %d", &k,&s);

  for(i = zero(s - 2*k);i<=k;i++){
    //if( s - i > 2*k)continue;
    for(j = zero(s - k - i);j<= min(k, s-i) ;j++){
      //if( s - i - j > k)continue;
      for(l = 0;l<=min(k, s - i -j);l++){
        if(s == i + j + l){
          count++;
          break;
        }
      }
    }
  }
  printf("%d\n",count );
  return 0;
}