链接:lg1439
题解
- 注意是n的全排列,所以用a串作为字典串将b串更改一下,例如a串3 2 1 4 5 b串1 2 3 4 5
- 更改之后b串变为3 2 1 4 5 ,求最长公共子序列变为求新b串的最长上升子序列
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using namespace std;
const int N=1e5+7;
const int inf=0x3f3f3f3f;
template <typename T>inline void read(T &x){
char c;int sign=1;x=0;
do{c=getchar();if(c=='-')sign=-1;}while(c<'0'||c>'9');
do{x=x*10+c-'0';c=getchar();}while(c>='0'&&c<='9');
x*=sign;
}
int id[N],a[N],n,dp[N],ans;
int main(){
read(n);
int x;
memset(dp,0x3f,sizeof dp);dp[0]=0;
rep(i,1,n){read(x);id[x]=i;}
rep(i,1,n){read(x);a[i]=id[x];}
rep(i,1,n){
if(a[i]>dp[ans])dp[++ans]=a[i];
else {
int k=lower_bound(dp+1,dp+ans+1,a[i])-dp;
dp[k]=min(dp[k],a[i]);
}
}
printf("%d\n",ans);
return 0;
}