ABC051 B - Sum of Three Integers

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atcoder

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# Problem

https://atcoder.jp/contests/abc051/tasks/abc051_b

Given integers K and S, report the number of combinations of integers X, Y, Z which satisfy 0≤X,Y,Z≤K0 \leq X, Y, Z \leq K and X+Y+Z=SX + Y + Z = S.

# Time complexity

O(K2)O(K^2)

# Solution

// C++ 14
#include <iostream>
#include <string>
#include <vector>
#include <list>
#include <algorithm>
#include <queue>
#include <stack>
#include <set>
#include <map>
#include <unordered_map>
#include <math.h>

#define ll long long
#define Int int
#define loop(x, start, end) for(Int x = start; x < end; x++)
#define loopdown(x, start, end) for(int x = start; x > end; x--)
#define rep(n) for(int x = 0; x < n; x++)
#define span(a,x,y) a.begin()+x,a.begin()+y
#define span_all(a) a.begin(),a.end()
#define len(x) (x.size())
#define last(x) (*(x.end()-1))

using namespace std;
#define MAX_K 2501
#define MAX_S 3 * MAX_K

Int K, S;

void input() {
  cin >> K >> S;
}

void solve() {
  Int count = 0;
  loop(x,0,K+1) {
    loop(y,0,K+1) {
      Int z = S - x - y;
      if (0 <= z && z <= K) count++;
    }
  }
  cout << count << endl;
}

int main(void) {
  input();
  solve();
}

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