1、CF #374 (Div. 2) D. Maxim and Array
2、总结：按绝对值最小贪心下去即可
3、题意：对n个数进行+x或-x的k次操作，要使操作之后的n个数乘积最小。
（1）优先队列
#include<bits/stdc++.h>
#define F(i,a,b) for (int i=a;i<b;i++)
#define FF(i,a,b) for (int i=a;i<=b;i++)
#define mes(a,b) memset(a,b,sizeof(a))
#define INF 0x3f3f3f3f
#define LL long long
using namespace std;
const int N=,MAX=; struct Num
{
int i;
LL val; //一开始用int，一直挖9
bool operator <(const Num &a1)const {
return abs(val)>abs(a1.val);
}
}a[N]; int main()
{
int n,k,num1;
LL x;
while(~scanf("%d%d%lld",&n,&k,&x))
{
priority_queue<Num>Q;
num1=;
F(i,,n){
scanf("%lld",&a[i].val);
a[i].i=i;
Q.push(a[i]);
if(a[i].val<)num1++;
}
Num ans;
while(k--){
ans=Q.top();Q.pop();
if(num1%) {
if(ans.val==){
ans.val+=x;
}else if(ans.val>){
ans.val+=x;
}else {
ans.val-=x;
}
}else {
if(ans.val==){
ans.val-=x;
if(ans.val<)num1++;
}else if(ans.val>){
ans.val-=x;
if(ans.val<)num1++;
}else {
ans.val+=x;
if(ans.val>=)num1--;
} }
a[ans.i]=ans;
Q.push(ans);
}
printf("%lld",a[].val);
F(i,,n)printf(" %lld",a[i].val);
puts(""); } return ;
}
（2）set
#include<bits/stdc++.h>
#define F(i,a,b) for (int i=a;i<b;i++)
#define FF(i,a,b) for (int i=a;i<=b;i++)
#define mes(a,b) memset(a,b,sizeof(a))
#define INF 0x3f3f3f3f
#define LL long long
using namespace std;
const int N=,MAX=; int main()
{
int n,k,flag;
LL x,a[N];
while(~scanf("%d%d%lld",&n,&k,&x))
{
flag=;
set<pair<LL,int> >S;
F(i,,n){
scanf("%lld",&a[i]);
if(a[i]<)flag^=;
S.insert(make_pair(abs(a[i]),i)); }
while(k--){
int pos=S.begin()->second;S.erase(S.begin());
if(flag){
if(a[pos]>=)a[pos]+=x;
else a[pos]-=x;
}else {
if(a[pos]>=){
a[pos]-=x;
if(a[pos]<)flag^=;
}
else {
a[pos]+=x;
if(a[pos]>=)flag^=;
}
}
S.insert(make_pair(abs(a[pos]),pos));
}
cout<<a[];
F(i,,n)printf(" %lld",a[i]);
cout<<endl; } return ;
}