Codeforces Round #267 (Div. 2)

A

#include <iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
#include<stdlib.h>
#include<vector>
#include<cmath>
#include<queue>
#include<set>
using namespace std;
#define N 100000
#define LL long long
#define INF 0xfffffff
const double eps = 1e-8;
const double pi = acos(-1.0);
const double inf = ~0u>>2;
int main()
{
    int n,i,j;
    int ans = 0;
    cin>>n;
    for(i = 1; i <= n; i++)
    {
        int x,y;
        scanf("%d%d",&x,&y);
        if(y-x>=2) ans++;
    }
    cout<<ans<<endl;
    return 0;
}

B

还以为是间接的朋友，写复杂了，没想到那么简单。

#include <iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
#include<stdlib.h>
#include<vector>
#include<cmath>
#include<queue>
#include<set>
using namespace std;
#define N 1010
#define LL long long
#define INF 0xfffffff
const double eps = 1e-8;
const double pi = acos(-1.0);
const double inf = ~0u>>2;
int a[N];
int fa[N];
int r[N];
int find(int x)
{
    if(x!=fa[x])
    {
        fa[x] = find(fa[x]);
        return fa[x];
    }
    return x;
}
int main()
{
    int n,m,k,i,j;
    cin>>n>>m>>k;
    for(i = 1 ;i <= m+1; i++) {fa[i] = i;r[i] = 1;}
    for(i = 1; i <= m+1; i++)
    scanf("%d",&a[i]);
    int ans = 0;
    for(i = 1 ; i <= m; i++)
    {
        int cnt = 0;
        for(int g = 0 ; g < n ;g++)
            if((a[m+1]&(1<<g))!=(a[i]&(1<<g))) cnt++;
            if(cnt<=k) ans++;
    }
//    for(i = 1; i <= m+1; i++)
//        for(j = 1; j <= m+1; j++)
//        {
//            if(i==j) continue;
//            int cnt = 0;
//            for(int g = 0 ; g < n ;g++)
//            if((i&(1<<g))!=(i&(1<<g))) cnt++;
//            if(cnt<=k)
//            {
//                int tx = find(i);
//                int ty = find(j);
//                if(tx!=ty)
//                {
//                    fa[tx] = ty;
//                    r[tx]+=r[ty];
//                }
//            }
//        }
//    int kk = find(m+1);
    cout<<ans<<endl;
    return 0;
}

　C

简单dp

#include <iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
#include<stdlib.h>
#include<vector>
#include<cmath>
#include<queue>
#include<set>
using namespace std;
#define N 5010
#define LL long long
#define INF 0xfffffff
const double eps = 1e-8;
const double pi = acos(-1.0);
const double inf = ~0u>>2;
int a[N];
LL dp[N][N];
LL sum[N];
int main()
{
    int n,m,k,i,j;
    cin>>n>>m>>k;
    for(i = 1; i <= n;  i++)
    {
        scanf("%d",&a[i]);
        sum[i] = sum[i-1]+a[i];
    }
    for(i = m; i <= n ;i++)
    {
        for(j = 1; j <= k; j++)
        dp[i][j] = max(dp[i-m][j-1]+sum[i]-sum[i-m],dp[i-1][j]);
    }
    cout<<dp[n][k]<<endl;
    return 0;
}

D

tarjan缩点+dfs

dfs的时候少写了else里面的内容。。一直wa到结束

#include <iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
#include<stdlib.h>
#include<vector>
#include<cmath>
#include<queue>
#include<set>
#include<map>
#include<stack>
using namespace std;
#define N 500010
#define M 500010
#define LL long long
#define INF 0xfffffff
const double eps = 1e-8;
const double pi = acos(-1.0);
const double inf = ~0u>>2;
struct node
{
    int u,v,next,w;
} edge[M];
int t,low[N],pre[N],sccno[N],head[N],scc,dep,vis[N],dis[N];
int dd1[N],dd2[N];
int dp[N];
int num[N],de[N];
vector<int>cd[N];
void init()
{
    t = 0;
    memset(head,-1,sizeof(head));
}
void add(int u,int v)
{
    edge[t].u  =u;
    edge[t].v = v;
    edge[t].next = head[u];
    head[u] = t++;
}
stack<int>s;
void dfs(int u)
{
    low[u] = pre[u] = ++dep;
    s.push(u);
    for(int i = head[u] ; i!=-1 ; i = edge[i].next)
    {
        int v = edge[i].v;
        if(!pre[v])
        {
            dfs(v);
            low[u] = min(low[u],low[v]);
        }
        else if(!sccno[v])
            low[u] = min(low[u],pre[v]);
    }
    if(low[u]==pre[u])
    {
        scc++;
        int minz = INF,sum=INF;
        for(;;)
        {
            int x = s.top();
            s.pop();
            if(minz>num[x])
            {
                minz = num[x];
                sum = dp[x];
            }
            else if(minz==num[x]) sum = min(dp[x],sum);
            sccno[x] = scc;
            if(x==u)break;
        }
        dd1[scc] = minz;
        dd2[scc] = sum;

    }
}
void find_scc(int n)
{
    scc=0;
    dep=0;
    memset(low,0,sizeof(low));
    memset(pre,0,sizeof(pre));
    memset(sccno,0,sizeof(sccno));
    for(int i = 1; i <= n ; i++)
        if(!pre[i])
            dfs(i);
}
map<string,int>f;
vector<int>ed[N];
char s1[N],s2[N];
int a[N];
int judge(char *str)
{
    int i,k;
    k= strlen(str);
    int cnt = 0;
    for(i = 0 ; i < k; i++)
        if(str[i]=='R')
            cnt++;
    return cnt;
}
int ddfs(int u)
{
    int i,j;
    for(i = 0 ; i< ed[u].size() ; i++)
    {
        int v = ed[u][i];
        if(!vis[v])
        {
            vis[v] = 1;
            int ss = ddfs(v);
            if(dd1[u]>=ss)
            {
                if(dd1[u]==ss)
                    dd2[u] = min(dd2[u],dd2[v]);
                else dd2[u] = dd2[v];
                dd1[u] = ss;
            }
        }
        else if(dd1[u]>=dd1[v])
        {
            if(dd1[u]==dd1[v]) dd2[u] = min(dd2[u],dd2[v]);
            else dd2[u] = dd2[v];
            dd1[u] = dd1[v];
        }
    }
    return dd1[u];
}
int main()
{
    init();
    int m,i,j,n;
    scanf("%d",&m);
    int g = 0;
    for(i = 1; i <= m ; i++)
    {
        scanf("%s",s1);
        int len = strlen(s1);
        for(j = 0 ; j <  len; j++) if(s1[j]>='a'&&s1[j]<='z') s1[j]-=32;
        if(!f[s1])
        {
            a[i] = ++g;
            f[s1] = g;
        }
        else a[i] = f[s1];
        num[a[i]] = judge(s1);
        dp[a[i]] = len;
    }
    scanf("%d",&n);
    for( i =1 ; i <= n ; i++)
    {
        int u,v;
        scanf("%s%s",s1,s2);
        int len1 =strlen(s1) ,len2 = strlen(s2);
        for(j = 0 ; j <  len1; j++) if(s1[j]>='a'&&s1[j]<='z') s1[j]-=32;
        for(j = 0 ; j <  len2; j++) if(s2[j]>='a'&&s2[j]<='z') s2[j]-=32;
        if(!f[s1])
        {
            u = ++g;
            f[s1] = g;
        }
        else u = f[s1];
        if(!f[s2])
        {
            v = ++g;
            f[s2] = g;
        }
        else v = f[s2];
        add(u,v);
        num[u] = judge(s1);
        num[v] = judge(s2);
        dp[u] = len1;
        dp[v] = len2;
        cd[u].push_back(v);
    }
    find_scc(g);
    for(i = 1 ; i <= g; i++)
    {
        int u = sccno[i];
        for(j = 0 ;j < cd[i].size() ; j++)
        {
            int v = sccno[cd[i][j]];
            if(v==u) continue;
            ed[u].push_back(v);
            de[v] = 1;
        }
    }
    memset(vis,0,sizeof(vis));
    for(i = 1 ; i <= scc; i++)
    {
        if(!de[i])
        {
            vis[i] = 1;
            ddfs(i);
        }
    }
    LL ans = 0,sum=0;
    for(i = 1 ; i<= m; i++)
    {
        int u = sccno[a[i]];
        //cout<<u<<" "<<dd2[u]<<endl;
        ans+=dd1[u];
        sum+=dd2[u];
    }
    cout<<ans<<" "<<sum<<endl;
    return 0;
}