2015亚洲区北京站网络赛

http://hihocoder.com/problemset/problem/1227

题意:给出平面上m个点,任选一个点为圆心,选最小的半径使得恰好n个点在圆内。

解法:枚举圆心,然后对所有点到该圆心距离排序,取第n大的距离作为半径,若第n+1大的在圆内或圆上不合法。

 

 1 //#define debug
 2 //#define txtout
 3 #include<cstdio>
 4 #include<cstdlib>
 5 #include<cstring>
 6 #include<cmath>
 7 #include<cctype>
 8 #include<ctime>
 9 #include<iostream>
10 #include<algorithm>
11 #include<vector>
12 #include<queue>
13 #include<stack>
14 #include<map>
15 #include<set>
16 #define mt(a,b) memset(a,b,sizeof(a))
17 using namespace std;
18 typedef long long LL;
19 const double eps=1e-8;
20 const double pi=acos(-1.0);
21 const int inf=0x3f3f3f3f;
22 const int M=1e2+10;
23 struct point {
24     double x,y;
25 } p[M];
26 double dist[M];
27 int n,m;
28 
29 double Square(double x) { ///平方
30     return x*x;
31 }
32 double Distance(point a,point b) { ///平面两点距离
33     return sqrt(Square(a.x-b.x)+Square(a.y-b.y));
34 }
35 
36 int choose(point c) {
37     for(int i=0; i<m; i++) {
38         dist[i]=Distance(c,p[i]);
39     }
40     sort(dist,dist+m);
41     double r=dist[n-1];
42     int int_r=(int)(r+1);
43     if(n<m&&dist[n]<int_r+eps)
44         return inf;
45     return int_r;
46 }
47 int solve() {
48     if(n>m) return -1;
49     int res=inf;
50     for(int i=0; i<m; i++) {
51         res=min(res,choose(p[i]));
52     }
53     if(res==inf) res=-1;
54     return res;
55 }
56 int main() {
57 #ifdef txtout
58     freopen("in.txt","r",stdin);
59     freopen("out.txt","w",stdout);
60 #endif
61     int t;
62     while(~scanf("%d",&t)) {
63         while(t--) {
64             scanf("%d%d",&m,&n);
65             for(int i=0; i<m; i++) {
66                 scanf("%lf%lf",&p[i].x,&p[i].y);
67             }
68             printf("%d\n",solve());
69         }
70     }
71     return 0;
72 }
View Code

 

B http://hihocoder.com/problemset/problem/1228

题意:模拟一行文本的输入操作。输入文本长度限制m,操作序列string,输出最后的文本。

操作L将光标左移,R光标右移,S切换插入和复写的输入模式,D删右边一个或选中区间,B删左边一个,C选区间,V将缓冲区复制一份。完全符合计算机复制粘贴等,细心模拟题。 

解法:读题,模拟。

 

  1 //#define debug
  2 //#define txtout
  3 #include<cstdio>
  4 #include<cstdlib>
  5 #include<cstring>
  6 #include<cmath>
  7 #include<cctype>
  8 #include<ctime>
  9 #include<iostream>
 10 #include<algorithm>
 11 #include<vector>
 12 #include<queue>
 13 #include<stack>
 14 #include<map>
 15 #include<set>
 16 #define mt(a,b) memset(a,b,sizeof(a))
 17 using namespace std;
 18 typedef long long LL;
 19 const double eps=1e-8;
 20 const double pi=acos(-1.0);
 21 const int inf=0x3f3f3f3f;
 22 const int M=1e4+10;
 23 char input[M];
 24 char output[M];
 25 char buffer[M];
 26 char save[M];
 27 int limit;
 28 int length_of_output;
 29 int length_of_buffer;
 30 int index_of_caret;
 31 int index_of_copy;
 32 bool overwrite_mode;
 33 bool start;
 34 void init(){
 35     index_of_caret=0;
 36     length_of_output=0;
 37     overwrite_mode=false;
 38     start=false;
 39 }
 40 void Insert(int id,char c){
 41     length_of_output++;
 42     for(int i=length_of_output-1;i>=id;i--){
 43         output[i]=output[i-1];
 44     }
 45     output[id]=c;
 46 }
 47 void Delete(int x,int y){
 48     for(int i=y+1;i<length_of_output;i++){
 49         output[x+i-y-1]=output[i];
 50     }
 51     length_of_output-=(y-x+1);
 52 }
 53 void Copy(int x,int y){
 54     length_of_buffer=0;
 55     for(int i=x;i<=y;i++){
 56         buffer[length_of_buffer++]=output[i];
 57     }
 58 }
 59 void Flip(bool &a){
 60     a=!a;
 61 }
 62 void solve_L(){
 63     if(index_of_caret) index_of_caret--;
 64 }
 65 void solve_R(){
 66     if(index_of_caret<length_of_output) index_of_caret++;
 67 }
 68 void solve_S(){
 69     Flip(overwrite_mode);
 70 }
 71 void solve_D(){
 72     if(start){
 73         if(index_of_caret<index_of_copy){
 74             Delete(index_of_caret,index_of_copy-1);
 75         }
 76         else{
 77             Delete(index_of_copy,index_of_caret-1);
 78             index_of_caret=index_of_copy;
 79         }
 80         Flip(start);
 81         return ;
 82     }
 83     if(index_of_caret<length_of_output){
 84         Delete(index_of_caret,index_of_caret);
 85     }
 86 }
 87 void solve_B(){
 88     if(index_of_caret){
 89         Delete(index_of_caret-1,index_of_caret-1);
 90         index_of_caret--;
 91     }
 92 }
 93 void solve_C(){
 94     if(start){
 95         if(index_of_caret<index_of_copy){
 96             Copy(index_of_caret,index_of_copy-1);
 97         }
 98         else{
 99             Copy(index_of_copy,index_of_caret-1);
100         }
101     }
102     else{
103         index_of_copy=index_of_caret;
104         length_of_buffer=0;
105     }
106     Flip(start);
107 }
108 void solve_V(){
109     if(overwrite_mode){
110         if(index_of_caret+length_of_buffer>limit) return ;
111         for(int i=0;i<length_of_buffer;i++){
112             output[index_of_caret+i]=buffer[i];
113         }
114         index_of_caret+=length_of_buffer;
115         length_of_output=max(length_of_output,index_of_caret);
116     }
117     else{
118         if(length_of_output+length_of_buffer>limit) return ;
119         int length_of_save=0;
120         for(int i=index_of_caret;i<length_of_output;i++){
121             save[length_of_save++]=output[i];
122         }
123         for(int i=0;i<length_of_buffer;i++){
124             output[index_of_caret+i]=buffer[i];
125         }
126         index_of_caret+=length_of_buffer;
127         for(int i=0;i<length_of_save;i++){
128             output[index_of_caret+i]=save[i];
129         }
130         length_of_output+=length_of_buffer;
131     }
132 }
133 void add(char c){
134     if(overwrite_mode){
135         if(index_of_caret==length_of_output&&length_of_output==limit) return ;
136         output[index_of_caret]=c;
137         if(index_of_caret==length_of_output) length_of_output++;
138     }
139     else{
140         if(length_of_output==limit) return ;
141         Insert(index_of_caret,c);
142     }
143     index_of_caret++;
144 }
145 void solve_by_type(char c){
146     if(c=='L') return solve_L();
147     if(c=='R') return solve_R();
148     if(c=='D') return solve_D();
149     if(c=='C') return solve_C();
150     start=false;
151     if(c=='B') return solve_B();
152     if(c=='S') return solve_S();
153     if(c=='V') return solve_V();
154     return add(c);
155 }
156 void solve(){
157     init();
158     for(int i=0;input[i];i++){
159         solve_by_type(input[i]);
160     }
161     output[length_of_output]=0;
162     if(length_of_output==0) strcpy(output,"NOTHING");
163 }
164 int main(){
165     #ifdef txtout
166     freopen("in.txt","r",stdin);
167     freopen("out.txt","w",stdout);
168     #endif
169     int t;
170     while(~scanf("%d",&t)){
171         while(t--){
172             scanf("%d%s",&limit,input);
173             solve();
174             puts(output);
175         }
176     }
177     return 0;
178 }
View Code

 

 H http://hihocoder.com/problemset/problem/1234

题意:给一个边长1的正方形,每次选每条边中点构成新的正方形,重复1000次,输入一个坐标k,求x=k这条直线与该图形交点个数。

解法:精度至少1e-10,枚举前30个竖线的x坐标存数组,然后测输入的坐标在哪个范围,每往前走一个范围答案+4,如果离0.5非常近,就是2000.

 

 1 //#define debug
 2 //#define txtout
 3 #include<cstdio>
 4 #include<cstdlib>
 5 #include<cstring>
 6 #include<cmath>
 7 #include<cctype>
 8 #include<ctime>
 9 #include<iostream>
10 #include<algorithm>
11 #include<vector>
12 #include<queue>
13 #include<stack>
14 #include<map>
15 #include<set>
16 #define mt(a,b) memset(a,b,sizeof(a))
17 using namespace std;
18 typedef long long LL;
19 const double eps=1e-10;
20 const double pi=acos(-1.0);
21 const int inf=0x3f3f3f3f;
22 const int M=1e2+10;
23 double x;
24 double y[M];
25 bool zero(double x){
26     return (x>0?x:-x)<eps;
27 }
28 void init(){
29     double add=0.25;
30     y[0]=0;
31     for(int i=1;i<30;i++){
32         y[i]=y[i-1]+add;
33         add*=0.5;
34     }
35 }
36 int solve(){
37     int res=0;
38     for(int i=0;i<30;i++){
39         if(zero(x-y[i])) return -1;
40         if(x<y[i]) return res;
41         res+=4;
42     }
43     return 2000;
44 }
45 int main(){
46     #ifdef txtout
47     freopen("in.txt","r",stdin);
48     freopen("out.txt","w",stdout);
49     #endif
50     init();
51     int t;
52     while(~scanf("%d",&t)){
53         while(t--){
54             scanf("%lf",&x);
55             printf("%d\n",solve());
56         }
57     }
58     return 0;
59 }
View Code

 

 

end

 

posted on 2015-10-26 13:07  gaolzzxin  阅读(144)  评论(0编辑  收藏  举报