CH Round #49 - Streaming #4 (NOIP模拟赛Day2)
A.二叉树的的根
题目:http://www.contesthunter.org/contest/CH%20Round%20%2349%20-%20Streaming%20%234%20(NOIP 模拟赛Day2)/二叉树的根
题解:自己yy一下就出来了。。。
如果有度数超过3的节点,则不可能成为2叉树,直接输出0即可
否则,树中度数为1和2的点都可以作为根
代码:
![](https://images.cnblogs.com/OutliningIndicators/ContractedBlock.gif)
1 var i,n,x,y,tot:longint; 2 a,d:array[0..150000] of longint; 3 procedure init; 4 begin 5 readln(n); 6 for i:=1 to n-1 do 7 begin 8 readln(x,y);inc(d[x]);inc(d[y]); 9 end; 10 end; 11 procedure main; 12 begin 13 tot:=0; 14 for i:=1 to n do 15 if d[i]>=4 then begin writeln(0);exit;end 16 else if d[i]<=2 then begin inc(tot);a[tot]:=i;end; 17 writeln(tot); 18 write(a[1]); 19 for i:=2 to tot do write(' ',a[i]); 20 end; 21 22 begin 23 init; 24 main; 25 end.
B.距离统计
题目:http://www.contesthunter.org/contest/CH%20Round%20%2349%20-%20Streaming%20%234%20(NOIP模拟赛Day2)/距离统计
题解:正解不可做。。。写暴力还写跪了。。。本来能骗50分,结果最后只有10分。。。
代码:
![](https://images.cnblogs.com/OutliningIndicators/ContractedBlock.gif)
1 var tmp,n,m,t,r,x,k:int64; 2 i,j:longint; 3 ans:int64; 4 procedure init; 5 begin 6 readln(n,m,t); 7 if n>m then begin tmp:=n;n:=m;m:=tmp;end; 8 end; 9 procedure main; 10 begin 11 for i:=1 to t do 12 begin 13 read(r);ans:=0; 14 if m>r then inc(ans,n*(m-r)); 15 if n>r then inc(ans,m*(n-r)); 16 for j:=1 to trunc(r/sqrt(2)) do 17 begin 18 x:=sqr(r)-sqr(j); 19 if x<sqr(j) then break; 20 if trunc(sqrt(x))=sqrt(x) then 21 begin 22 k:=trunc(sqrt(x)); 23 if m>k then inc(ans,2*(n-j)*(m-k)); 24 if n>k then inc(ans,2*(n-k)*(m-j)); 25 end; 26 end; 27 write(ans,' '); 28 end; 29 end; 30 begin 31 init; 32 main; 33 end.
C.电阻网络
题目:http://www.contesthunter.org/contest/CH%20Round%20%2349%20-%20Streaming%20%234%20(NOIP模拟赛Day2)/电阻网络
题解:我表示电阻都不会算了。。。果断弃疗。。。