A:超级大水题，不解释：
代码：
1 #include<iostream> 2 #include<algorithm> 3 using namespace std; 4 int a,b; 5 int main() 6 { 7 int n,m,ma=0,mi=9999999,mb=9999999; 8 cin>>n>>m; 9 for(int i=0; i<n; i++) 10 { 11 cin>>a; 12 if(a>ma)ma=a; 13 if(a<mi)mi=a; 14 } 15 for(int i=0; i<m; i++) 16 { 17 cin>>b; 18 if(mb>b)mb=b; 19 } 20 if(mi*2>ma)ma=mi*2; 21 if(ma>=mb)cout<<"-1"; 22 else cout<<ma; 23 return 0; 24 }
B:很简单，打个标记，dfs解决；
1 #include<cstdio> 2 #include<vector> 3 #include<algorithm> 4 #define maxn 100005 5 using namespace std; 6 vector<int>ve[maxn]; 7 int belong[maxn],to[maxn]; 8 bool vis[maxn],dead[maxn]; 9 void dfs(int x,int f) 10 { 11 if(to[x]==0||belong[to[x]]==1||dead[to[x]])return; 12 ve[f].push_back(to[x]); 13 dfs(to[x],f); 14 } 15 16 int main() 17 { 18 int n; 19 scanf("%d",&n); 20 for(int i=1; i<=n; i++)scanf("%d",&belong[i]); 21 for(int i=1; i<=n; i++) 22 { 23 scanf("%d",&to[i]); 24 if(to[i]!=0) 25 { 26 if(vis[to[i]]) 27 dead[to[i]]=1; 28 else vis[to[i]]=1; 29 } 30 } 31 for(int i=1; i<=n; i++) 32 { 33 if(belong[i]==1) 34 { 35 ve[i].push_back(i); 36 dfs(i,i); 37 } 38 } 39 int ma=0,k; 40 for(int i=1; i<=n; i++)if(ve[i].size()>ma) 41 { 42 ma=ve[i].size(); 43 k=i; 44 } 45 printf("%d ",ma); 46 for(int i=ma-1; i>=0; i--)printf("%d ",ve[k][i]); 47 return 0; 48 }
C：很简单，排个序，然后按照规则输出就行；
1 #include<cstdio> 2 #include<algorithm> 3 #define maxn 100005 4 using namespace std; 5 6 struct bomb 7 { 8 int x,y; 9 bool operator<(const bomb &t)const 10 { 11 if(abs(x)==abs(t.x))return abs(y)<abs(t.y); 12 return abs(x)<abs(t.x); 13 } 14 } bo[maxn]; 15 16 int main() 17 { 18 int n,ans=0; 19 scanf("%d",&n); 20 for(int i=0; i<n; i++) 21 { 22 scanf("%d%d",&bo[i].x,&bo[i].y); 23 if(bo[i].x==0||bo[i].y==0)ans+=4; 24 else ans+=6; 25 } 26 sort(bo,bo+n); 27 printf("%d ",ans); 28 for(int i=0; i<n; i++) 29 { 30 if(bo[i].x!=0) 31 { 32 printf("1 %d ",abs(bo[i].x)); 33 puts(bo[i].x>0?"R":"L"); 34 } 35 if(bo[i].y!=0) 36 { 37 printf("1 %d ",abs(bo[i].y)); 38 puts(bo[i].y>0?"U":"D"); 39 } 40 puts("2"); 41 if(bo[i].x!=0) 42 { 43 printf("1 %d ",abs(bo[i].x)); 44 puts(bo[i].x>0?"L":"R"); 45 } 46 if(bo[i].y!=0) 47 { 48 printf("1 %d ",abs(bo[i].y)); 49 puts(bo[i].y>0?"D":"U"); 50 } 51 puts("3"); 52 } 53 return 0; 54 }