3.27考试总结（hnoi难度）

1 duel
1.1 Description
K·⁄¶("“uƒ¢y%¥§H5|+ (?1’m" ’m·ø?1§z<k§⁄k<⁄§lm?0,1,2...§zg ‹‰ª«mS(?1ߧo?1cgß" 3gߥ§Win The Duel§Xkı§K?¿§ {=§=KlŁ˛¥K§{ØC§,Ølm ›#?0,1,2..." “‹3e(" )K3S§kn¶("K§{n−1¶fi†—Ł˛§KI J\§KƒØ§ƒƒUWin The Duelߌƒı§ K3\S?§XkıYƒß…Œ§?"
1.2 Input
11knŒn,c,K§L«(Œ!ßgŒ!K" e51n−1Œ§£ªfi†—Ł(" c1U^S£ªzgß3cS¥«m"
1.3 Output
ŒL«K3S¥?"
1.4 Sample Input
5 3 3
1
0
2
4
1 3
0 1
0 1
1.5 Sample Output
2
1
1.6 Data 50% : n ≤ 5000" 100% : n ≤ 100000§y?Œ3intS"
3
2 city
2.1 Description
C·I§ƒI[·¢‰|⁄/(§z¢‰k{w"CIl ¥!:8S˜veu,v ∈ S§K?¿3u,v Æ·»:pkp ∈ S" S{w8¥!:{w§\Izø{w"du›fl!”C§ zU‹k¢‰{wu)Cz§\I£zU˜{w"
2.2 Input
11kŒn,m§L«!:Œu)CzUŒ§¥¢‰?1n" 11nŒ§1iŒwiL«1i¢‰—'{w" e5n−11§z1Œx,y§L«x,y¢‰mk>º" e5m1§z1Œu,v§L«¢‰u{wCzv"
2.3 Output m + 11§1i1£ª1i−1UY"
2.4 Sample Input
6 3
-7 2 -6 2 9 -5
1 2
2 3
1 4
2 5
2 6
5 9
3 8
1 10
2.5 Sample Output
11
11
19
31
4
2.6 Data
20% : m = 0" 40% : n ≤ 20000,m ≤ 10000" 80% : m ≤ 30000" 100% : 1 ≤ n,m ≤ 200000,−1000 ≤ wi,v ≤ 1000"

　　

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　　今天考试打了两个暴力，第一题是纯暴力的啦。第二题打的是一个dp，修改也只修改当前路径上的值。按道理来说这个复杂度是对的，但是我们还是可以旋转树，修改树高进行优化的说。另外第三题简直太难，完全写不了，题面我也不打算丢上来了。

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我打的暴力：

T1

#include<iostream>
#include<cstdio>
#include<cstdlib>
#include<algorithm>
#include<cmath>
#include<cstring>
int n,c,k,i,j,x,y,a[5010],w[5010],l[5010],r[5010],maxl,next[5010],tot,wz1,wz2,ma,wz3,ans;
bool f=true;
using namespace std;
int main()
{
freopen("duel.in","r",stdin); freopen("duel.out","w",stdout);
cin>>n>>c>>k;
for (i=1;i<n;i++) scanf("%d",&w[i]);
for (i=1;i<=c;i++) {scanf("%d%d",&l[i],&r[i]); l[i]++; r[i]++;}
for (j=1;j<=n;j++)
{
for (i=n;i>j;i--) {a[i]=w[i-1]; next[i]=i+1;}
a[j]=k; next[j]=j+1; f=true; tot=0; next[0]=1;
for (i=1;i<j;i++) {a[i]=w[i]; next[i]=i+1;}
i=0;
while (f && i<c)
{
i++;
x=0; wz1=0;
while (x<l[i]-1) {wz1=next[wz1];x++;}
y=x; wz2=wz1; ma=0; wz3=-1;
while (y-x<=r[i]-l[i])
{
wz2=next[wz2]; y++;
if (a[wz2]>ma) {ma=a[wz2]; wz3=wz2;}
}
if (wz3==j) tot++;
if (j>wz1 && j<=wz2 && a[j]<ma) f=false;
next[wz1]=wz3;
next[wz3]=next[wz2];
}
if (tot>maxl) {maxl=tot; ans=j;}
}
cout<<ans-1;
return 0;
}

T2

#include<iostream>
#include<cstdio>
#include<algorithm>
#include<cstdlib>
#include<cmath>
#include<cstring>
#include<vector>
#define ll int
ll i,j,k,x,n,m,val[200010],y,dad[200010],fa,f[200010][2],bj[200010];
bool ff=true;
using namespace std;
vector <ll> a[200010];
ll max(ll x,ll y) {if (x>y) return x;else return y;}
void ss(ll sd)
{
for (ll i=0;i<a[sd].size();i++) if (bj[a[sd][i]]==0) { bj[a[sd][i]]=bj[sd]+1; dad[a[sd][i]]=sd; ss(a[sd][i]);}
ll tot=0,maxn=-0x7fffffff;
for (ll i=0;i<a[sd].size();i++) if (bj[a[sd][i]]>bj[sd]) {if (f[a[sd][i]][1]>0) tot+=f[a[sd][i]][1]; maxn=max(maxn,f[a[sd][i]][1]);}
f[sd][1]=val[sd]+tot;
f[sd][0]=maxn;
}
void xiugai(int sd)
{
ll tot=0,maxn=-0x7fffffff;
for (ll i=0;i<a[sd].size();i++) if (bj[a[sd][i]]>bj[sd]) {if (f[a[sd][i]][1]>0) tot+=f[a[sd][i]][1]; maxn=max(maxn,f[a[sd][i]][1]);}
f[sd][1]=val[sd]+tot;
f[sd][0]=maxn;
if (dad[sd]!=0) xiugai(dad[sd]);
}
int main()
{
freopen("city.in","r",stdin); freopen("city.out","w",stdout);
cin>>n>>m;
for (i=1;i<=n;i++) scanf("%d",&val[i]);
for (i=1;i<n;i++)
{
scanf("%d%d",&x,&y);
a[x].push_back(y);
a[y].push_back(x);
}
fa=n/2;
//while (dad[fa]!=0) fa=dad[fa];
m++;
while (m--)
{
if (!ff) {scanf("%d%d",&x,&y); val[x]=y; xiugai(x); ll ans=-0x7fffffff; for (i=1;i<=n;i++) {ans=max(ans,f[i][1]); if (f[i][0]!=0 && f[i][0]>ans) ans=f[i][0]; } printf("%d\n",ans); continue;}
//for (i=1;i<=n;i++) {f[i][0]=0; f[i][1]=val[i]; bj[i]=0;}
bj[fa]=1;
if (ff) ss(fa);
ff=false;
ll ans=-0x7fffffff;
for (i=1;i<=n;i++) {ans=max(ans,f[i][1]); if (f[i][0]!=0 && f[i][0]>ans) ans=f[i][0]; }
printf("%d\n",ans);
//scanf("%d%d",&x,&y);
//val[x]=y;
}
return 0;
}