Informatics Olympiad preliminary round questions pascal in recent years

Sorry, I only have word form, you give me the email address, and I'll send it over.

Eight-digit binary, the maximum is 11111111 = 2 7 + 2 6 + 2 5 + 2 4 + 2 3 + 2 1 + 2 0 = 255, from 0 to 255, there are a total of 256 binary serial numbers, 00000000 does not contain 1, so there are only 255 eight-digit serial numbers containing "1".

The first 00000001 and the second 00000010, two consecutive serial numbers contain only one 1,255-1) 2=127

The answer is 128? I think it's 127

By induction: two-digit sequence: 00, 01, 10, 11, four numbers, only one contains an even number of 1s, which is half of the four numbers minus one.

Three-digit sequences: 000, 001, 010, 011, 100, 101, 110, 111, only three of the eight sequences contain an even number of 1s, which is the average minus one.

Four-digit sequence: 0000, 0001, 0010, 0011, 0100, 0101, 0110, 0111, 1000, 1001, 1010, 1011, 1100, 1101, 1110, 1111, only 7 of the sixteen sequences contain an even number of 1s, or the average minus one ......

This is a permutation problem: 8 binaries do not interfere with each other, and only 2 are selected, i.e., 0 or 1, and the serial numbers that meet the meaning of the question are 0 1s, 2 1s, 4 1s, 6 1s, and 8 1s.

Since there are 8 digits, each bit is either 1 or 0, and the number of 1 is even, so the number of 1 can be

When 0 is 1, when 8 is also 1, it is a permutation and combination problem, such as 2 out of 8, 4, and 6, that is, c82, c84, c86, so the final answer is 1 + c82 + c84 + c86 + 1 = 128

This is the preliminary question of the NOIP 2011 popularization group, and I just finished the exam.

The preliminary round is easy. The key to the rematch.

5. Improve the procedure (the first 6 blanks, 3 points for each space, the last 5 blanks, 2 points for each space, a total of 28 points).

1 (find the k-th largest number) Given a sequence of unordered regular integers of length 1000000 and another number n(1<=n<=1000000), then find the nth largest number in the sequence (about the nth largest number: e.g. the third largest number in the sequence is 4) in a similar way to quicksort

var a:array[1..1000000] of integer;

n,m,ans:integer;

procedure swap(var a,b:integer);

var t:integer;

beginif (a<>b) then begin

t:=a; a:=b; b:=t;

end;end;

function findkth(left,right,n:integer):integer;

var tmp,value,i,j:integer;

beginif left=right then exit(left);

tmp:=random(right-left)+left;

swap(a[tmp],a[left]);

value:=___

i:=left; j:=right;

while in then begin dec(j); exit(__end;

exit(i);

end;var i:integer;

beginrandomize;

ans:=-1;

m:=5;for i:=1 to m do

read(a[i]);

read(n);

ans:=findkth(1,m,n);

writeln(a[ans]);

end.2 (number in matrix) has a matrix A of n*n (1 n 5000) for 1 i0 do begin

if a[n,j]k do

beginwhile (_and (i>1) do dec(i);

while (_and (j<=n) do inc(j);end;

end;var i,j:integer;

beginread(n);

for i:=1 to n do

for j:=1 to n do

read(a[i,j]);

read(k);

findkposition;

writeln(answerx,' ',answery);

end.

The Informatics Olympiad is a discipline competition aimed at promoting the popularization of computers, focusing on cultivating students' abilities, so that potential and talented students can exercise and develop in the competition. In recent years, the organization of informatics competitions has gradually become standardized and perfect, and a competition network of "prefecture-level cities, provinces (municipalities directly under the central government), and national and international competitions has been basically formed. The relevant events are briefly introduced as follows:

National Youth Informatics (Computer) Olympiad Divisional League:

Prior to the 1995 NOI event, the first National Youth Informatics (Computer) Olympiad Divisional League was held in order to expand the coverage and take into account that most provinces, municipalities and autonomous regions have been conducting provincial competitions for many years. Taking into account the knowledge level of students of different grades, and in order to encourage more students to actively participate, the competition is divided into improvement groups and popularization groups, and is divided into junior and semi-finals, so as to form an echelon and ensure that the annual competition activities have a relatively broad and solid foundation.

From 1995 to 2001, a total of seven sessions of the National Youth Informatics Olympiad Divisional League were held, which were held once a year, with individual awards (provincial and national level), player level certificates, and awards for outstanding participating schools. Guangdong Youth Informatics (Computer) Olympiad Finals (GDOI):

The Provincial Informatics Olympiad is a high-level and influential discipline competition. The teams will be organized by each city to participate in the competition, and the quota will be dynamically allocated once a year. Since 1984, the Olympiad in Guangdong Province has flourished. Awards have individuals.

First, second and third prizes, female contestants.

First, second and third places, the total score of the school group is 1-8, and the total score of the city group is 1-8. National Youth Informatics (Computer) Olympiad (NOI): A national youth discipline competition sponsored by the Chinese Computer Science Society and in line with the International Informatics Olympiad.

In 1984, the first national computer competition was held. The competition is organized by various provinces and cities and is held once a year. Awards have individuals.

First, second and third prizes, female contestants.

First, second and third places, the total score of each provincial team is lined up. International Youth Olympiad in Informatics (ICAI): Held once a year, teams from participating countries participate.

The first: 35 (I don't know why).

The second: n2 + 2n 3 + 3n 4 + .m-1) nm+1 (this is a fundamental property of binary trees, which can be mathematically deduced, but it's too long, just remember it, this head is the most basic).

The third: use recursion to do, recursive: s[1,1]=1 s[n,k]=s[n-1,k]+s[n-1,k-1] (put n balls into k boxes can be divided into n-1 balls into k boxes, and the kernel swim is to put this ball into any one of k boxes, + let this ball be alone in a box, that is, s[n-1,k-1]);