前言

在短暂的比赛时间中，我发现本菜鸡越是功于心计想$AC$，越是拿不到分，所以。。。

我不写比赛了$JOJO!$

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成绩

$J$表示初中，$H$表示高中后面加的是几年级

$Rank$	$Person$	$Score$	$A$	$B$	$C$
$17$	$(J-3)WYC$	$190$	$100$	$0$	$90$
$24$	$(H-1)ZZY$	$175$	$35$	$40$	$100$
$30$	$(H-2)HJW$	$160$	$100$	$0$	$60$
$36$	$(J-3)ZYC$	$140$	$75$	$0$	$65$
$43$	$(J-3)XXY$	$130$	$80$	$5$	$45$
$50$	$(J-3)HJQ$	$105$	$0$	$5$	$100$
$52$	$(J-3)HZB$	$100$	$55$	$5$	$40$
$75$	$(H-2)LZX$	$70$	$25$	$5$	$40$
$77$	$(H-1)WHF$	$65$	$60$	$5$	$0$
$88$	$(H-1)QYH$	$40$	$0$	$40$	$0$
$92$	$(J-3)XJQ$	$35$	$30$	$5$	$0$
$92$	$(J-3)LRZ$	$35$	$0$	$0$	$35$
$100$	$(J-3)LW$	$100$	$10$	$0$	$0$
$104$	$(H-2)YJY$	$0$	$0$	$0$	$0$

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正题

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$T1:jzoj6286,P4442-$走格子$(Portal)$【$BFS,SPFA$】

链接:
https://blog.csdn.net/Mr_wuyongcong/article/details/98976611

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$T2:jzoj6287-$扭动的树【区间$dp$】

链接:
https://blog.csdn.net/Mr_wuyongcong/article/details/98978000

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$T3:jzoj6288-$旋转子段【优雅的暴力】

链接:
https://blog.csdn.net/Mr_wuyongcong/article/details/98987138

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总结

今天$T1$之前见过，然后就写了完了以后就自己举出了一个反例$???$然后放着去看后面，$T3$只会$O(n^2)$暴力就写了个。然后回来刚$T1$，发现有一个简单的点的方法就写完了，然后就切掉了。然后看$T2$，这不是区间$dp$吗？然后只会写$O(n^4)$的就写了骗分
看题预估分
$$100+0+60=160$$
做题预估分
$$100+70+60=230$$
实际获得分
$$100+0+90=190$$
$T3$竟然能水这么高分，$T2$竟然$MLE$了???连$n^3$的数组都开不了???

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$Someofcode$

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$T2MLEcode$

#include<cstdio>
#include<cstring>
#include<algorithm>
#define ll long long
using namespace std;
const ll N=310;
struct node{ll k,p;
}a[N];
ll n,f[N][N][N],g[N][N],ans,s[N][N];
bool v[N][N];
bool cmp(node x,node y)
{return x.k<y.k;}
int main()
{freopen("tree.in","r",stdin);freopen("tree.out","w",stdout);scanf("%lld",&n);for(ll i=1;i<=n;i++)scanf("%lld%lld",&a[i].k,&a[i].p);sort(a+1,a+1+n,cmp);for(ll i=1;i<=n;i++)f[i][i][i]=g[i][i]=a[i].p;for(ll i=1;i<=n;i++)for(ll j=i;j<=n;j++){v[i][j]=(__gcd(a[i].k,a[j].k)==1);s[i][j]=s[i][j-1]+a[j].p;}if(n<=120){for(ll l=2;l<=n;l++){for(ll i=1;i<=n-l+1;i++){ll j=i+l-1;for(ll k=i;k<=j;k++){ll A=0,B=0;for(ll z=i;z<k;z++)if(!v[z][k]) A=max(A,f[z][i][k-1]);for(ll z=k+1;z<=j;z++)if(!v[k][z]) B=max(B,f[z][k+1][j]);f[k][i][j]=A+B+s[i][j];if(!A&&k>i||!B&&k<j) f[k][i][j]=-2147483647;if(l==n) ans=max(ans,f[k][i][j]);}}}}else{for(ll l=2;l<=n;l++){for(ll i=1;i<=n-l+1;i++){ll j=i+l-1;for(ll k=i;k<=j;k++){f[k][i][j]=g[i][k-1]+g[k+1][j]+s[i][j];g[i][j]=max(g[i][j],f[k][i][j]);}if(l==n) ans=max(ans,g[i][j]);}}}if(!ans) printf("-1");else printf("%lld",ans);
}

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$T390ptscode$

#include<cstdio>
#include<cstring>
#include<algorithm>
using namespace std;
const int N=101000;
int n,a[N],s[N],ans,maxs;
int main()
{freopen("rotate.in","r",stdin);freopen("rotate.out","w",stdout);scanf("%d",&n);for(int i=1;i<=n;i++)scanf("%d",&a[i]),s[i]=s[i-1]+(a[i]==i);for(int i=1;i<=n;i++){int l=i,r=a[i];ans=0;if(l>r) swap(l,r);for(int j=0;j<=r-l;j++)if(a[l+j]==r-j) ans++;maxs=max(maxs,s[n]-s[r]+s[l-1]+ans);//printf("%d,%d %d\n",l,r,ans);}printf("%d",maxs);
}

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后记(次日)

话说昨晚写比赛去了就没来得及写完$blog$。不过比赛也是水到了$Rank80$的高名次