2016-11-15试题解题报告

#include<cstdio>
#include<algorithm>
using namespace std;
inline int read(){
    register int x=0;bool f=1;
    register char ch=getchar();
    while(ch<‘0‘||ch>‘9‘){if(ch==‘-‘)f=0;ch=getchar();}
    while(ch>=‘0‘&&ch<=‘9‘){x=(x<<3)+(x<<1)+ch-‘0‘;ch=getchar();}
    return f?x:-x;
}
const int N=1e5+10;
int lson[N],rson[N],a[N];
int n,ans;
int len,r,b[N],c[N];
void dfs(int x){
    if(lson[x]) dfs(lson[x]);
    b[++len]=x;
    if(rson[x]) dfs(rson[x]);
}
void LIS(){
    for(int p,i=1;i<=len;i++){
        int x=a[b[i]]-i;
        if(x>=c[r]){
            c[++r]=x;
        }
        else{
            p=upper_bound(c+1,c+r+1,x)-c;
            c[p]=x;
        }
    }
}
#define name "binary"
int main(){
    n=read();
    for(int i=1;i<=n;i++) a[i]=read();
    for(int i=2,fa,son;i<=n;i++){
        fa=read();son=read();
        if(!son) lson[fa]=i;
        else rson[fa]=i;
    }
    dfs(1);
    LIS();
    printf("%d\n",len-r);
    return 0;
}　

//std既丑由慢~~~还是暴力快
#include<cstdio>
#include<algorithm>
using namespace std;
const int N=5e5+10;
int n,len=-1,a[N],ans[N];
#define name "pair"
int main(){
    freopen(name".in","r",stdin);
    freopen(name".out","w",stdout);
    scanf("%d",&n);
    for(int i=1;i<=n;i++) scanf("%d",a+i);
    for(int i=1;i<=n;i++){//枚举a[k] 
        int L=i,R=i;//枚举a[k]所能管辖的最远边界 
        while(L-1>=1&&a[L-1]%a[i]==0) L--;
        while(R+1<=n&&a[R+1]%a[i]==0) R++;
        if(R-L>len){
            len=R-L;
            ans[ans[0]=1]=L;
        }
        else if(R-L==len){
            ans[++ans[0]]=L;
        }
    }
    sort(ans+1,ans+ans[0]+1);
    ans[0]=unique(ans+1,ans+ans[0]+1)-(ans+1);
    printf("%d %d\n",ans[0],len);
    for(int i=1;i<=ans[0];i++) printf("%d ",ans[i]);
    fclose(stdin);
    fclose(stdout);
    return 0;
}
/*30分存档 
#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<iostream>
#include<algorithm>
#include<queue>
#include<stack>
#include<vector>
#include<map>
using namespace std;
inline int read(){
    register int x=0;bool f=1;
    register char ch=getchar();
    while(ch<‘0‘||ch>‘9‘){if(ch==‘-‘)f=0;ch=getchar();}
    while(ch>=‘0‘&&ch<=‘9‘){x=(x<<3)+(x<<1)+ch-‘0‘;ch=getchar();}
    return f?x:-x;
}
const int N=1e3+10;
const int M=9e6+10;
int n,a[N],xmin[N][N];
struct node{
    int l,r,val;
    node(int _l=0,int _r=0,int _val=0){
        l=_l;r=_r;val=_val;
    }
    bool operator <(const node &b)const{
        if(val==b.val) return l<b.l;
        return val>b.val;
    }
}fs[M];
int cnt,num,zmx;
#define name "pair"
int main(){
    freopen(name".in","r",stdin);
    freopen(name".out","w",stdout);
    n=read();
    for(int i=1;i<=n;i++) a[i]=read();
    for(int i=1;i<=n;i++){
        xmin[i][i]=a[i];
        for(int j=i+1;j<=n;j++){
            xmin[i][j]=min(xmin[i][j-1],a[j]);
        }
    }
    //for(int i=1;i<=n;i++){
    //    for(int j=i;j<=n;j++){
    //        printf("min[%d,%d]: %d\n",i,j,xmin[i][j]);
    //    }
    //}
    for(int i=1;i<=n;i++){
        for(int k,v,j=i+1;j<=n;j++){
            for(k=i;k<=j;k++){
                if(a[k]%xmin[i][j]) break;
            }
            if(k>j){
                if((v=j-i)>=zmx){
                    zmx=v;
                    fs[++cnt]=node(i,j,v);
                }
            }
        }
    }
    sort(fs+1,fs+cnt+1);
    for(int i=1;i<=cnt;i++) if(fs[i].val!=zmx){num=i-1;break;}
    if(!num||!zmx){
        printf("%d %d\n",n,0);
        for(int i=1;i<=n;i++) printf("%d ",i);
        return 0;
    }
    printf("%d %d\n",num,zmx);
    for(int i=1;i<num;i++) printf("%d ",fs[i].l);printf("%d",fs[num].l);
    fclose(stdin);
    fclose(stdout);
    return 0;
}*/

#include<cstdio>
#include<cstring>
#include<algorithm>
#define ll long long
using namespace std;
inline int read(){
    register int x=0,f=1;
    register char ch=getchar();
    while(ch<‘0‘||ch>‘9‘){if(ch==‘-‘)f=-1;ch=getchar();}
    while(ch>=‘0‘&&ch<=‘9‘){x=x*10+ch-‘0‘;ch=getchar();}
    return x*f;
}
const int N=55;
const int mod=1e9+7;
int n,p[N],C[N][N],dp[N][N];
int dfs(int len,int low){
    if(dp[len][low]!=-1) return dp[len][low];
    if(len==1) return dp[len][low]=1;
    int &res=dp[len][low];res=0;
    int t[N],m=0;
    for(int i=1;i<=n;i++){
        if(p[i]>=low&&p[i]<len+low){
            t[++m]=p[i];
        }
    }
    for(int j,k,i=1;i<=m;i++){
        swap(t[i],t[i+1]);
        for(j=1;j<=i;j++) if(t[j]>=low+i) break;
        for(k=i+1;k<=m;k++) if(t[k]<low+i) break;
        if(j>i&&k>m){
            ll tmp=((ll)dfs(i,low)*(ll)dfs(m-i,low+i))%mod;
            tmp=tmp*C[m-2][i-1]%mod;
            res=(res+tmp)%mod;
        }
        swap(t[i],t[i+1]);
    }
    return res;
}
#define name "swap"
int main(){
    freopen(name".in","r",stdin);
    freopen(name".out","w",stdout);
    memset(dp,-1,sizeof dp); 
    n=read();
    for(int i=1;i<=n;i++) p[i]=read();
    for(int i=0;i<=n;i++){
        C[i][0]=1;
        for(int j=1;j<=i;j++){
            C[i][j]=(C[i-1][j-1]+C[i-1][j])%mod;
        }
    }
    dfs(n,0);
    printf("%d",dp[n][0]!=-1?dp[n][0]:0);
    fclose(stdin);
    fclose(stdout);
    return 0;
}
/*
//读懂题目后，暴力30分(改出来的) 
#include<cstdio>
#include<algorithm>
using namespace std;
const int N=1e5+10;
const int mod=1e9+7;
int n,dn,a[N],b[N],c[N];
int ans;
bool judge(){
    for(int i=0;i<n;i++) b[i]=i;
    for(int i=0;i<dn;i++) swap(b[c[i]],b[c[i]+1]);
    for(int i=0;i<n;i++) if(a[i]!=b[i]) return 0;
    return 1;
}
#define name "swap"
int main(){
    freopen(name".in","r",stdin);
    freopen(name".out","w",stdout);
    scanf("%d",&n);
    for(int i=0;i<n;i++) scanf("%d",&a[i]);
    for(int i=0;i<n;i++) b[i]=i;
    dn=n-1;
    for(int i=0;i<dn;i++) c[i]=i;
    do{
        if(judge()) ans++;
        if(ans>=mod) ans-=mod;
    }while(next_permutation(c,c+dn));
    printf("%d",ans);
    fclose(stdin);
    fclose(stdout);
    return 0;
}*/