CodeForces

分为奇数组，每组有奇数个数，这样就决定 n 必须为奇数

满足上述条件后，只要开头结尾的数为奇数就一定满足了

#include <iostream>#include <cstdio>#include <cstdlib>#include <cstring>#include <string>#include <cmath>#include <set>#include <map>#include <stack>#include <queue>#include <ctype.h>#include <vector>#include <algorithm>#include <sstream>#define PI acos(-1.0)#define in freopen("in.txt", "r", stdin)#define out freopen("out.txt", "w", stdout)using namespace std;typedef long long ll;const int maxn = 100 + 7, INF = 0x3f3f3f3f, mod = 1e9 + 7;int n, a[maxn];int main() {    scanf("%d", &n);    if(n % 2 == 0) { puts("No"); return 0; }    for(int i = 0; i < n; ++i) {        scanf("%d", & a[i]);    }    if(a[0]%2 && a[n-1]%2) puts("Yes");    else puts("No");    return 0;}