T1-8第八题 移动问题CodeForces - 515A amc第一次考试2018.12.8

Someday, Drazil wanted to go on date with Varda. Drazil and Varda live on Cartesian plane. Drazil's home is located in point (0, 0) and Varda's home is located in point (a, b). In each step, he can move in a unit distance in horizontal or vertical direction. In other words, from position (x, y) he can go to positions (x + 1, y), (x - 1, y), (x, y + 1) or (x, y - 1).

Unfortunately, Drazil doesn't have sense of direction. So he randomly chooses the direction he will go to in each step. He may accidentally return back to his house during his travel. Drazil may even not notice that he has arrived to (a, b) and continue travelling.

Luckily, Drazil arrived to the position (a, b) successfully. Drazil said to Varda: "It took me exactly s steps to travel from my house to yours". But Varda is confused about his words, she is not sure that it is possible to get from (0, 0) to (a, b) in exactly s steps. Can you find out if it is possible for Varda?

Input
You are given three integers a, b, and s ( - 109 ≤ a, b ≤ 109, 1 ≤ s ≤ 2·109) in a single line.

Output
If you think Drazil made a mistake and it is impossible to take exactly s steps and get from his home to Varda's home, print "No" (without quotes).

Otherwise, print "Yes".

#include
using namespace std;

int pos(int a) {
    return a * (-1);
}

int main() {
    int a, b, c;
    cin >> a >> b >> c;
    if(a<0)
    a = pos(a);
    if(b<0)
    b = pos(b);
    if(c<0)
    c = pos(c);
    int min = a + b;//最少要走min步
    if ((c >= min && (c - min) % 2 == 0) || c == min)cout << "Yes";//考虑到可能到了位置又走出去
//因此要保证走的步数减去最少的步数是2的倍数
    else cout << "No";

}