2017 ACM/ICPC Asia Regional Shenyang Online

A string string string

判断一个字符串恰出现k次的子串个数。

建立SAM，对每个节点统计出现次数cnti，先对字符串的n个后缀的cnti+=1，然后将每个节点的值更新父节点。

#include<bits/stdc++.h>
using namespace std;
#define For(i,n) for(int i=1;i<=n;i++)
#define Fork(i,k,n) for(int i=k;i<=n;i++)
#define ForkD(i,k,n) for(int i=n;i>=k;i--)
#define Rep(i,n) for(int i=0;i<n;i++)
#define ForD(i,n) for(int i=n;i;i--)
#define RepD(i,n) for(int i=n;i>=0;i--)
#define Forp(x) for(int p=pre[x];p;p=next[p])
#define Forpiter(x) for(int &p=iter[x];p;p=next[p])
#define Lson (o<<1)
#define Rson ((o<<1)+1)
#define MEM(a) memset(a,0,sizeof(a));
#define MEMI(a) memset(a,0x3f,sizeof(a));
#define MEMi(a) memset(a,128,sizeof(a));
#define MEMx(a,b) memset(a,b,sizeof(a));
#define INF (0x3f3f3f3f)
#define F (1000000007)
#define pb push_back
#define mp make_pair
#define fi first
#define se second
#define vi vector<int>
#define pi pair<int,int>
#define SI(a) ((a).size())
#define Pr(kcase,ans) printf("Case #%d: %lld\n",kcase,ans);
#define PRi(a,n) For(i,n-1) cout<<a[i]<<' '; cout<<a
<<endl;
#define PRi2D(a,n,m) For(i,n) { \
For(j,m-1) cout<<a[i][j]<<' ';\
cout<<a[i][m]<<endl; \
}
#pragma comment(linker, "/STACK:102400000,102400000")
#define ALL(x) (x).begin(),(x).end()
#define gmax(a,b) a=max(a,b);
#define gmin(a,b) a=min(a,b);
typedef long long ll;
typedef long double ld;
typedef unsigned long long ull;
ll mul(ll a,ll b){return (a*b)%F;}
ll add(ll a,ll b){return (a+b)%F;}
ll sub(ll a,ll b){return ((a-b)%F+F)%F;}
void upd(ll &a,ll b){a=(a%F+b%F)%F;}
inline int read()
{
int x=0,f=1; char ch=getchar();
while(!isdigit(ch)) {if (ch=='-') f=-1; ch=getchar();}
while(isdigit(ch)) { x=x*10+ch-'0'; ch=getchar();}
return x*f;
}
#define MAXN (200100)
#define Sigmasize (26)
class SAM {
public:
char s[MAXN];
int n;
void mem(char *_s){
n=strlen(_s);
memcpy(s,_s,sizeof(char)*(n+5));
Rep(i,2*n+10) {
Rep(j,26) son[i][j]=0;
pre[i]=step[i]=0;
}
last=tot=0;
}

int son[MAXN][Sigmasize+1],pre[MAXN],step[MAXN],last,tot;
int cnt[MAXN];

void extend(char ch)
{
step[++tot]=step[last]+1;
int p=last,np=tot;

for(;!son[p][ch];p=pre[p]) son[p][ch]=np;
if (!p) pre[np]=1;
else {
int q=son[p][ch];
if (step[q]==step[p]+1) pre[np]=q;
else {
step[++tot]=step[p]+1;
int nq=tot;
memcpy(son[nq],son[q],sizeof(son[q]));
pre[nq]=pre[q];
pre[q]=pre[np]=nq;
for(;son[p][ch]==q;p=pre[p]) son[p][ch]=nq;
}
}
last=np;
cnt[last]++;
}

void build(){
Rep(i,2*n+10) cnt[i]=0;
last=tot=1;
Rep(i,n) extend(s[i]-'a');
}
int c[MAXN],q[MAXN],len[MAXN];
void calc(int k) {
Rep(i,2*n+10) c[i]=0;
For(i,tot) c[step[i]]++;
For(i,tot) c[i]+=c[i-1];
For(i,tot) q[c[step[i]]--]=i;
int p=1;
ll ans=0;
ForD(i,tot) {
int u=q[i];
if (pre[u]>0) cnt[pre[u]]+=cnt[u];
if (cnt[u]==k) {
ans+=step[u]-step[pre[u]];
}
}
printf("%lld\n",ans);
}
}S;
char s[MAXN];

int main()
{
//  freopen("A.in","r",stdin);
//  freopen(".out","w",stdout);
int T;T=read();
while(T--) {
int k=read();
scanf("%s",s);
S.mem(s);
S.build();
S.calc(k);
}

return 0;
}

D array array array

求一个序列删除k个元素后是否能单调递增或递减。

签到

#include<bits/stdc++.h>
using namespace std;
#define For(i,n) for(int i=1;i<=n;i++)
#define Fork(i,k,n) for(int i=k;i<=n;i++)
#define ForkD(i,k,n) for(int i=n;i>=k;i--)
#define Rep(i,n) for(int i=0;i<n;i++)
#define ForD(i,n) for(int i=n;i;i--)
#define RepD(i,n) for(int i=n;i>=0;i--)
#define Forp(x) for(int p=pre[x];p;p=next[p])
#define Forpiter(x) for(int &p=iter[x];p;p=next[p])
#define Lson (o<<1)
#define Rson ((o<<1)+1)
#define MEM(a) memset(a,0,sizeof(a));
#define MEMI(a) memset(a,0x3f,sizeof(a));
#define MEMi(a) memset(a,128,sizeof(a));
#define MEMx(a,b) memset(a,b,sizeof(a));
#define INF (0x3f3f3f3f)
#define F (1000000007)
#define pb push_back
#define mp make_pair
#define fi first
#define se second
#define vi vector<int>
#define pi pair<int,int>
#define SI(a) ((a).size())
#define Pr(kcase,ans) printf("Case #%d: %lld\n",kcase,ans);
#define PRi(a,n) For(i,n-1) cout<<a[i]<<' '; cout<<a
<<endl;
#define PRi2D(a,n,m) For(i,n) { \
For(j,m-1) cout<<a[i][j]<<' ';\
cout<<a[i][m]<<endl; \
}
#pragma comment(linker, "/STACK:102400000,102400000")
#define ALL(x) (x).begin(),(x).end()
#define gmax(a,b) a=max(a,b);
#define gmin(a,b) a=min(a,b);
typedef long long ll;
typedef long double ld;
typedef unsigned long long ull;
ll mul(ll a,ll b){return (a*b)%F;}
ll add(ll a,ll b){return (a+b)%F;}
ll sub(ll a,ll b){return ((a-b)%F+F)%F;}
void upd(ll &a,ll b){a=(a%F+b%F)%F;}
inline int read()
{
int x=0,f=1; char ch=getchar();
while(!isdigit(ch)) {if (ch=='-') f=-1; ch=getchar();}
while(isdigit(ch)) { x=x*10+ch-'0'; ch=getchar();}
return x*f;
}
#define MAXN (100100)
int n,m,a[MAXN],d[MAXN],f[MAXN],len=0;
void LIS()
{
MEM(f)
memset(d,128,sizeof(d));
d[len=0]=INF;
ForD(i,n)
{
int l=0,r=len,ans=0;
while (l<=r)
{
int m=l+r>>1;
if (a[i]<=d[m]) ans=m,l=m+1;
else r=m-1;
}
f[i]=ans+1;len=max(len,f[i]);
d[f[i]]=max(d[f[i]],a[i]);
}
}

int main()
{
//  freopen("D.in","r",stdin);
//  freopen(".out","w",stdout);

int T=read();
while(T--) {
n=read();int k=read();
For(i,n) a[i]=read();
LIS();
int p=len;
For(i,n/2) swap(a[i],a[n-i+1]);
LIS();
int p2=len;
if(n-k<=p||n-k<=p2) {
printf("A is a magic array.\n");
}else puts("A is not a magic array.");
}

return 0;
}

mustedge mustedge mustedge

还在MLE