Codeforces Round #563 (Div. 2) B. Ehab Is an Odd Person

链接：https://codeforces.com/contest/1174/problem/B

题意：

You're given an array aa of length nn. You can perform the following operation on it as many times as you want:

• Pick two integers ii and jj (1≤i,j≤n)(1≤i,j≤n) such that ai+ajai+aj is odd, then swap aiai and ajaj.

What is lexicographically the smallest array you can obtain?

An array xx is lexicographically smaller than an array yy if there exists an index ii such that xi<yixi<yi, and xj=yjxj=yj for all 1≤j<i1≤j<i. Less formally, at the first index ii in which they differ, xi<yi

思路：

记录偶数和奇数的个数，只要数组内同时有偶数和奇数，无论几个都可以使数组完全排序。

代码:

#include <bits/stdc++.h>

using namespace std;

typedef long long LL;
const int MAXN = 3e5 + 10;
const int MOD = 1e9 + 7;
int n, m, k, t;

int a[MAXN];

int main()
{
    cin >> n;
    bool flag1 = false, flag2 = false;
    for (int i = 1;i <= n;i++)
    {
        cin >> a[i];
        if (a[i] % 2 == 0)
            flag1 = true;
        if (a[i] % 2 == 1)
            flag2 = true;
    }
    if (flag1 && flag2)
        sort(a+1, a+1+n);
    for (int i = 1;i <= n;i++)
        cout << a[i] << ' ';
    cout << endl;

    return 0;
}