Codeforces Beta Round #29 (Div. 2, Codeforces format)
http://codeforces.com/contest/29
A
1 #include<bits/stdc++.h>
2 using namespace std;
3 #define lson l,mid,rt<<1
4 #define rson mid+1,r,rt<<1|1
5 #define sqr(x) ((x)*(x))
6 #define pb push_back
7 #define maxn 1000005
8 typedef long long ll;
9 typedef unsigned long long ull;
10 const ull MOD=257;
11 /*#ifndef ONLINE_JUDGE
12 freopen("1.txt","r",stdin);
13 #endif */
14
15
16 int main(){
17 #ifndef ONLINE_JUDGE
18 // freopen("1.txt","r",stdin);
19 #endif
20 std::ios::sync_with_stdio(false);
21 int n;
22 cin>>n;
23 int a[105],b[105];
24 for(int i=1;i<=n;i++){
25 cin>>a[i]>>b[i];
26 }
27 int flag=0;
28 for(int i=1;i<=n;i++){
29 for(int j=1;j<=n;j++){
30 if(i!=j){
31 if(a[i]+b[i]==a[j]&&a[j]+b[j]==a[i]){
32 flag=1;
33 }
34 }
35 }
36 }
37 if(flag) cout<<"YES"<<endl;
38 else cout<<"NO"<<endl;
39 }
B
模拟
1 #include<bits/stdc++.h>
2 using namespace std;
3 #define lson l,mid,rt<<1
4 #define rson mid+1,r,rt<<1|1
5 #define sqr(x) ((x)*(x))
6 #define pb push_back
7 #define maxn 1000005
8 typedef long long ll;
9 typedef unsigned long long ull;
10 const ull MOD=257;
11 /*#ifndef ONLINE_JUDGE
12 freopen("1.txt","r",stdin);
13 #endif */
14
15
16 int main(){
17 #ifndef ONLINE_JUDGE
18 // freopen("1.txt","r",stdin);
19 #endif
20 std::ios::sync_with_stdio(false);
21 double l,d,v,g,r;
22 cin>>l>>d>>v>>g>>r;
23 double ans=0;
24 if(v*g>d) ans=l/v;
25 else{
26 l-=d;
27 double t=d/v;
28 ans=t;
29 double tt=g+r;
30 int flag=0;
31 while(t>=0){
32 t-=g;
33 if(t>=0){
34 t-=r;
35 }
36 if(t<0) flag=1;
37 }
38 // cout<<t<<endl;
39 if(flag==1){
40 ans-=t;
41 }
42 ans+=l/v;
43 }
44 printf("%.7f\n",ans);
45 }
C
找出一个度为1的点，然后跑dfs。因为值为1e9，所以需要离散化
1 #include<bits/stdc++.h>
2 using namespace std;
3 #define lson l,mid,rt<<1
4 #define rson mid+1,r,rt<<1|1
5 #define sqr(x) ((x)*(x))
6 #define pb push_back
7 #define maxn 1000005
8 typedef long long ll;
9 typedef unsigned long long ull;
10 const ull MOD=257;
11 /*#ifndef ONLINE_JUDGE
12 freopen("1.txt","r",stdin);
13 #endif */
14
15 int n;
16 vector<int>ve;
17 int a[100005];
18 int b[100005];
19 int d[100005];
20 vector<int>V[100005];
21
22 int getid(int x){
23 return lower_bound(ve.begin(),ve.end(),x)-ve.begin()+1;
24 }
25
26 void dfs(int pos,int pre){
27 cout<<ve[pos-1]<<" ";
28 for(int i=0;i<V[pos].size();i++){
29 if(V[pos][i]!=pre){
30 dfs(V[pos][i],pos);
31 }
32 }
33 }
34
35 int main(){
36 #ifndef ONLINE_JUDGE
37 // freopen("1.txt","r",stdin);
38 #endif
39 std::ios::sync_with_stdio(false);
40 cin>>n;
41 for(int i=1;i<=n;i++){
42 cin>>a[i]>>b[i];
43 ve.pb(a[i]);
44 ve.pb(b[i]);
45 }
46 sort(ve.begin(),ve.end());
47 ve.erase(unique(ve.begin(),ve.end()),ve.end());
48 int pos,pos1,pos2;
49 for(int i=1;i<=n;i++){
50 pos1=getid(a[i]);
51 pos2=getid(b[i]);
52 d[pos1]++,d[pos2]++;
53 V[pos1].pb(pos2);
54 V[pos2].pb(pos1);
55 }
56 for(int i=1;i<=n;i++){
57 pos1=getid(a[i]);
58 pos2=getid(b[i]);
59 if(d[pos1]==1){
60 pos=pos1;
61 break;
62 }
63 if(d[pos2]==1){
64 pos=pos2;
65 break;
66 }
67 }
68 dfs(pos,0);
69 }
D
跑两个叶子结点的最短路，看看最后的个数是不是2*n-1
1 #include<bits/stdc++.h>
2 using namespace std;
3 #define lson l,mid,rt<<1
4 #define rson mid+1,r,rt<<1|1
5 #define sqr(x) ((x)*(x))
6 #define pb push_back
7 #define maxn 1000005
8 typedef long long ll;
9 typedef unsigned long long ull;
10 const ull MOD=257;
11 /*#ifndef ONLINE_JUDGE
12 freopen("1.txt","r",stdin);
13 #endif */
14
15 int n;
16 vector<int>ve[305];
17 int vis[305];
18 int d[305];
19 vector<int>ans;
20
21
22 void dfs(int pos,int pre,int last,vector<int>tmp){
23 vis[pos]=1;
24 if(pre!=0) {
25 tmp.pb(pos);
26 }
27 if(pos==last){
28 for(int i=0;i<tmp.size();i++){
29 ans.pb(tmp[i]);
30 }
31 return;
32 }
33 for(int i=0;i<ve[pos].size();i++){
34 if(!vis[ve[pos][i]]&&ve[pos][i]!=pre){
35 dfs(ve[pos][i],pos,last,tmp);
36 }
37 }
38 }
39
40 int main(){
41 #ifndef ONLINE_JUDGE
42 freopen("1.txt","r",stdin);
43 #endif
44 std::ios::sync_with_stdio(false);
45 cin>>n;
46 int u,v;
47 for(int i=1;i<n;i++){
48 cin>>u>>v;
49 ve[u].pb(v);
50 ve[v].pb(u);
51 d[u]++,d[v]++;
52 }
53 int co=0;
54 for(int i=2;i<=n;i++){
55 if(d[i]==1){
56 co++;
57 }
58 }
59 vector<int>son;
60 son.pb(1);
61 for(int i=1;i<=co;i++){
62 cin>>u;
63 son.pb(u);
64 }
65 son.pb(1);
66 ans.pb(1);
67 for(int i=0;i<son.size()-1;i++){
68 memset(vis,0,sizeof(vis));
69 vector<int>tmp;
70 tmp.clear();
71 dfs(son[i],0,son[i+1],tmp);
72 }
73 if(ans.size()==2*n-1){
74 for(int i=0;i<ans.size();i++){
75 cout<<ans[i]<<" ";
76 }
77 cout<<endl;
78 }
79 else{
80 cout<<-1<<endl;
81 }
82 }
E
bfs搜索，思路很有趣
标记是用A和B的相对位置进行标记的，懂了这一点这题就解决了
1 #include<bits/stdc++.h>
2 using namespace std;
3 #define lson l,mid,rt<<1
4 #define rson mid+1,r,rt<<1|1
5 #define sqr(x) ((x)*(x))
6 #define pb push_back
7 #define maxn 1000005
8 typedef long long ll;
9 typedef unsigned long long ull;
10 /*#ifndef ONLINE_JUDGE
11 freopen("1.txt","r",stdin);
12 #endif */
13 int n,m;
14 vector<int>ve[505];
15 int pre[505][505][2];
16 bool book[505][505];
17 vector<int>ans[2];
18
19 bool bfs(){
20 pre[1][n][0]=-1;
21 pair<int,int>p,pp;
22 p=make_pair(1,n);
23 queue<pair<int,int> >Q;
24 Q.push(p);
25 while(!Q.empty()&&pre[n][1][0]==0){
26 p=Q.front();
27 Q.pop();
28 int p1=p.first,p2=p.second;
29 for(int i=0;i<ve[p1].size();i++){
30 if(!book[ve[p1][i]][p2]){
31 book[ve[p1][i]][p2]=1;
32 for(int j=0;j<ve[p2].size();j++){
33 if(ve[p1][i]!=ve[p2][j]){
34 if(pre[ve[p1][i]][ve[p2][j]][0]==0){
35 pre[ve[p1][i]][ve[p2][j]][0]=p1;
36 pre[ve[p1][i]][ve[p2][j]][1]=p2;
37 pp=make_pair(ve[p1][i],ve[p2][j]);
38 Q.push(pp);
39 }
40 }
41 }
42 }
43 }
44 }
45 if(pre[n][1][0]==0) return false;
46 int x=n,y=1,z;
47 while(x>0){
48 ans[0].pb(x);
49 ans[1].pb(y);
50 z=x;
51 x=pre[x][y][0];
52 y=pre[z][y][1];
53 }
54 return true;
55 }
56
57 int main(){
58 #ifndef ONLINE_JUDGE
59 freopen("1.txt","r",stdin);
60 #endif
61 std::ios::sync_with_stdio(false);
62 cin>>n>>m;
63 int u,v;
64 for(int i=1;i<=m;i++){
65 cin>>u>>v;
66 ve[u].pb(v);
67 ve[v].pb(u);
68 }
69 if(bfs()){
70 cout<<ans[0].size()-1<<endl;
71 for(int i=0;i<2;i++){
72 for(int j=ans[i].size()-1;j>=0;j--){
73 cout<<ans[i][j]<<" ";
74 }
75 cout<<endl;
76 }
77 }
78 else{
79 cout<<-1<<endl;
80 }
81
82 }
原文地址：https://www.cnblogs.com/Fighting-sh/p/10381368.html
时间： 2024-10-09 17:53:28