2017 国庆湖南 Day1

卡特兰数

#include<cstdio>
#include<cstring>
#include<algorithm>

using namespace std;

int f[];

int main()
{
    freopen("stack.in","r",stdin);
    freopen("stack.out","w",stdout);
    int n;
    scanf("%d",&n);
    f[]=; f[]=;
    for(int i=;i<=n;i++)
        for(int j=;j<=i;j++)
            f[i]=(f[i]+f[j-]*f[i-j])%;
    printf("%d",f[n]);
}

没看到取模的高精

#include<cstdio>
#include<cstring>
#include<algorithm>

using namespace std;

struct node
{
    int len,a[];

    node()
    {
        len=;
        memset(a,,sizeof(a));
    }

    void operator = (int k)
    {
        a[]=k; len=;
    }

    void operator = (node b)
    {
        len=b.len;
        for(int i=;i<=len;i++) a[i]=b.a[i];
    }

    node operator * (int b)
    {
        node tmp;
        for(int i=;i<=len;i++) tmp.a[i]=a[i]*b;
        for(int i=;i<=len;i++) tmp.a[i+]+=tmp.a[i]/,tmp.a[i]%=;
        tmp.len=tmp.a[len+] ? len+ : len;
        while(tmp.a[tmp.len]>=) tmp.a[++tmp.len]=tmp.a[tmp.len-]/,tmp.a[tmp.len-]%=;
        return tmp;
    }  

    node operator / (int b)
    {
        node tmp,an;
        for(int i=len,j=;i;i--,j++)  tmp.a[j]=a[i];
        int x=;
        for(int i=;i<=len;i++)
        {
            x=x*+tmp.a[i];
            if(x>=b)
            {
                an.a[i]=x/b;
                x-=an.a[i]*b;
            }
        }
        int L=;
        for(int i=;i<=len;i++)
            if(an.a[i])
            {
                for(int j=len,k=;j>=i;j--,L++,k++) tmp.a[k]=an.a[j];
                break;
            }
        tmp.len=L;
        return tmp;
    }

    void print()
    {
        for(int i=len;i;i--) printf("%d",a[i]);
    }

}f[];

int main()
{
    int n;
    scanf("%d",&n);
    f[]=; f[]=;
    for(int i=;i<=n;i++) f[i]=f[i-]*(*i-)/(i+);
    f[n].print();
}

加权并查集

#include<cstdio>

using namespace std;

#define N 30001

int fa[N],under[N],siz[N];

int find(int i)
{
    if(i!=fa[i])
    {
        int f=find(fa[i]);
        under[i]+=under[fa[i]];
        return fa[i]=f;
    }
    return i;
}

void unionn(int x,int y)
{
    int X=find(x),Y=find(y);
    under[X]+=siz[Y];
    siz[Y]+=siz[X];
    fa[X]=Y;
}

int main()
{
    freopen("cube.in","r",stdin);
    freopen("cube.out","w",stdout);
    int n,m;
    scanf("%d",&n); m=n;
    for(int i=;i<=n;i++) fa[i]=i,siz[i]=;
    char s[]; int x,y;
    while(m--)
    {
        scanf("%s",s);
        if(s[]=='M')
        {
            scanf("%d%d",&x,&y);
            unionn(x,y);
        }
        else
        {
            scanf("%d",&x);
            find(x);
            printf("%d\n",under[x]);
        }
    }
}

区间DP

#include <cstdio>
#include <algorithm>
#include <iostream>
#include <cstring>

using namespace std;

const int N =  + ;

int dp[N][N];
int n;
char s[N];
int num[N], col[N], tot;

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

    scanf("%s", s + );
    n = strlen(s + );
    int now = s[] - '', cnt = ;
    for (int i = ; i <= n; i ++)
    {
        if (s[i] - '' == now)
        {
            cnt ++;
        }
        else
         {
            num[++ tot] = cnt;
            col[tot] = now;
            cnt = ;
            now = s[i] - '';
        }
    }
    num[++ tot] = cnt;
    col[tot] = now;

    for (int i = ; i <= tot; i ++) dp[i][i] =  - num[i];

    for (int len = ; len <= tot; len ++)
    {
        for (int i = , j = i + len - ; j <= tot; i ++, j ++)
        {
            dp[i][j] = ;
            if (col[i] == col[j])
            {
                dp[i][j] = min(dp[i][j], dp[i + ][j - ] + (num[i] + num[j] <  ?  : ));
                for (int k = i + ; k < j; k ++)
                    if (col[k] == col[i]) dp[i][j] = min(dp[i][j], dp[i + ][k - ] + dp[k + ][j - ]);
            }
            for (int k = i; k < j; k ++)    dp[i][j] = min(dp[i][j], dp[i][k] + dp[k + ][j]);
        }
    }
    printf("%d\n", dp[][tot]);
    return ;
}

75分大爆搜

#include<cstdio>
#include<cstring>

#define N 201

using namespace std;

int n,len;

int l,r,tot;

char s[N];
int col[N];

int ans=;

void find(int x)
{
    l=x-; r=x+; tot=;
    if(col[x]!=-) tot++;
    while(col[x]==- && x>) x--;
    if(x && col[x]!=-)
    {
        while(col[l]==col[x] || col[l]==-)
        {
            if(!l) break;
            if(col[l]==col[x]) tot++;
            l--;
            if(!l) break;
        }
    }
    if(col[x]==- || !x)
        while(col[x]==- && x<len) x++;
    while(col[r]==col[x] || col[r]==-)
    {
        if(r==len+) break;
        if(col[r]==col[x]) tot++;
        r++;
        if(r==len+) break;
    }
}

void dfs(int sum,int last)
{
    if(sum>=ans) return;
    if(sum>len*) return;
    if(!n) { ans=sum; return; }
    int m[N]; bool f; int tmp=n;
    for(int i=;i<=len;i++) m[i]=col[i];
    for(int i=last;i<=len;i++)
        if(col[i]!=-)
        {
            f=false;
            find(i);
            if(tot>=) f=true;
            n-=tot;
            for(int j=l+;j<i;j++) col[j]=-;
            for(int j=r-;j>=i;j--) col[j]=-;
            while(n)
            {
                find(i);
                if(tot>=)
                {
                    n-=tot;
                    for(int j=l+;j<i;j++) col[j]=-;
                    for(int j=r-;j>=i;j--) col[j]=-;
                }
                else break;
            }
            if(f) dfs(sum+,i+);
            else dfs(sum+,i+);
            n=tmp;
            for(int j=;j<=len;j++) col[j]=m[j];
        }
}

int main()
{
    freopen("zuma.in","r",stdin);
    freopen("zuma.out","w",stdout);
    scanf("%s",s+);
    len=strlen(s+); n=len;
    for(int i=;i<=len;i++) col[i]=s[i]=='';
    dfs(,);
    printf("%d",ans);
}