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题解
[jzoj 4255] ACM {DP+优化}
[jzoj 4256]平均数{二分答案+巧妙做法+前缀和优化}
[jzoj 4257] 着色 {组合计数}
今天，考得不好，能拿的分没有拿到。而且还看错了题目，第一题打了我好久的最小费用最大流——然而题目要去的是“非空的连续一段”第二道题，范围开小了——第三题莫名WA(我理解错题目的意思了！！！)（悲惨世界）
比赛程序
第一题费用流
#include<cstdio>
#include<algorithm>
#include<queue>
#include<cstring>
#define N 1010
#define INF (0x3f3f3f3f)
using namespace std;
int cnt,n,ans,head[N<<1],S,T;
struct edge{int next,to,flow,cost;}a[N<<3];
struct mincostmaxflow{
int d[N<<1],Mn[N<<1],fa[N<<1]; bool vis[N<<1]; queue<int>q;
int calc(){
int res=0;
while (1){
memset(d,63,sizeof(d)); d[S]=0; Mn[S]=INF; q.push(S);
while (!q.empty()){
int x=q.front(); q.pop(); vis[x]=0;
for (int i=head[x];~i;i=a[i].next){
int to=a[i].to;
if (!a[i].flow||d[to]<=d[x]+a[i].cost) continue;
d[to]=d[x]+a[i].cost; fa[to]=i; Mn[to]=min(Mn[x],a[i].flow);
if (!vis[to]) vis[to]=1,q.push(to);
}
}
if (d[T]==INF) return res;
res+=d[T]*Mn[T]; int p=T;
while (p!=S){
a[fa[p]].flow-=Mn[T];
a[fa[p]^1].flow+=Mn[T];
p=a[fa[p]^1].to;
}
}
}
}MCMF;
void add_edge(int from,int to,int flow,int cost){
a[cnt]=(edge){head[from],to,flow,cost}; head[from]=cnt++;
a[cnt]=(edge){head[to],from,0,-cost}; head[to]=cnt++;
}
int main(){
memset(head,-1,sizeof(head));
scanf("%d",&n); int k;
S=n+4; T=n+5;
for (int i=1;i<=3;i++)
for (int j=1;j<=n;j++)
{
scanf("%d",&k);
add_edge(i+n,j,1,k);
add_edge(j,j+1,INF,k);
}
for (int i=1;i<=3;i++) add_edge(S,i+n,1,0);
for (int i=1;i<=n;i++) add_edge(i,T,1,0);
return 0&printf("%d",MCMF.calc());
}
第一题没有时间调试的暴力
#include<cstdio>
#include<algorithm>
#define fre(x) freopen(#x".in","r",stdin);freopen(#x".out","w",stdout)
using namespace std;
int n,a[150001],q[150001],w[150001],e[150001],ans=1e8;
int main(){
fre(acm);
scanf("%d",&n);
for (int i=1;i<=n;i++){scanf("%d",&q[i]); q[i]+=q[i-1];}
for (int i=1;i<=n;i++){scanf("%d",&w[i]); w[i]+=w[i-1];}
for (int i=1;i<=n;i++){scanf("%d",&e[i]); e[i]+=e[i-1];}
for (int i=1;i<n;i++)
for (int j=i+1;j<=n;j++){
ans=min(ans,q[i]-q[0]+w[j]-w[i]+e[n]-e[j]);
ans=min(ans,w[i]-w[0]+e[j]-e[i]+q[n]-q[j]);
ans=min(ans,e[i]-e[0]+q[j]-q[i]+w[n]-w[j]);
}
printf("%d",ans);
}
第二题暴力
#include<cstdio>
#include<algorithm>
#define fre(x) freopen(#x".in","r",stdin);freopen(#x".out","w",stdout)
#define ll long long
using namespace std;
ll n,k,a[30001]; double b[30001],ans;
int main(){
fre(average);
scanf("%lld%lld",&n,&k);
for(ll i=1;i<=n;i++) scanf("%lld",&a[i]),b[i]=b[i-1]+a[i]*1.0;
for(ll i=k;i<=n;i++) for (ll j=i;j<=n;j++) ans=max(ans,(b[j]-b[j-i])/(i*1.0));
printf("%lf",ans);
}
第三题WA程序
#include<cstdio>
#define fre(x) freopen(#x".in","r",stdin);freopen(#x".out","w",stdout)
#define ll long long
using namespace std;
ll n,k;
ll ksm(ll x,ll y){ll ret=1; for (;y;y>>=1,x*=x) if (y&1) ret*=x; return ret;}
ll huan(ll x,ll y){return ksm(y-1,x)+ksm(-1,x)*(y-1);}
int main(){
fre(color);
scanf("%lld%lld",&n,&k);
if (n==1){
printf("%lld",k*ksm(k-1,19));
} else if (n==2){
printf("%lld",huan(3,k)*2*ksm(k-1,3));
} else if (n==3){
printf("%lld",k*ksm(k-1,3));
} else if (n==4){
printf("%lld",k*ksm(k-1,13));
} else if (n==5){
printf("%lld",huan(3,k)*2);
} else if (n==6){
} else if (n==7){
printf("%lld",huan(3,k)*2*ksm(k-1,3));
} else if (n==8){
printf("%lld",huan(30,k));
}
}