原题传送门
若一个数
,则
若一个数
,则
所以把所有大于等于0的数变成负的,如果有奇数个数,乘积是负的
所以把绝对值最大的负数变成正的,易证最优
Code:
#include <bits/stdc++.h>
#define maxn 100010
using namespace std;
int n, a[maxn];
inline int read(){
int s = 0, w = 1;
char c = getchar();
for (; !isdigit(c); c = getchar()) if (c == '-') w = -1;
for (; isdigit(c); c = getchar()) s = (s << 1) + (s << 3) + (c ^ 48);
return s * w;
}
int main(){
n = read();
for (int i = 1; i <= n; ++i){
a[i] = read();
if (a[i] >= 0) a[i] = -a[i] - 1;
}
if (n & 1){
int p = 0;
for (int i = 1; i <= n; ++i)
if (a[p] > a[i]) p = i;
a[p] = -a[p] - 1;
}
for (int i = 1; i <= n; ++i) printf("%d ", a[i]);
return 0;
}