Description
Jan Łukasiewicz was a Polish logician and philosopher best
known for Polish notation.
Reverse Polish notation
Reverse Polish notation (RPN), also known as Polish
postfix notation or simply postfix notation, is a
mathematical notation in which operators follow their
operands, in contrast to Polish notation (PN), in
which operators precede their operands. It does not
need any parentheses as long as each operator has
a fixed number of operands.
You need to write a program that transforms an infix
expression to a equivalent RPN according to the
following specifications.
1. The infix expression is in the input file in the
format of one character per line, with a
maximum of 50 lines. For example,
(1+1)*(4*5+1)-4 would be in the form:
(
1
+
1
)
*
(
4
*
5
+
1
)
–
4
2. There will be only one infix expression in the input file, and it will be an expression with a valid syntax.
3. All operators are binary operators +, -, *, / .
4. The operands will be one digit numerals: 0, 1, 2, … , 9.
5. The operators * and / have the highest precedence. The operators + and – have the lowest precedence.
Operators at the same precedence level associate from left to right. Parentheses act as grouping symbols that override the operator precedence.
Input
There will be multiple lines in the input file as specified above.
Output
The output file will have a postfix expression all on one line with no whitespace between symbols and a single newline
character at the end.
Example
Input:
(
1
+
1
)
*
Page 2/2
(
4
*
5
+
1
)
–
4
Output:
11+45*1+*4-
Page 1/2
Albert’s Dream
Albert has a dream: he wants to create his own dictionary (Merriam Webster is his idol and he hopes to have his own name
on a thick book one day). Albert realizes that he does not know enough words to create a complete dictionary. But he has
many many books and if he could only get all of the unique words out of those, he would be happy.
You are Albert’s best friend and majoring in computer
science, so you offer to help with processing all the
texts and selecting only the unique words. You are
going to write a program that processes text and
produces a list of unique words in alphabetical order.
Before you do that, Albert gives you his definition of a
word. A word is a sequence of one or more
consecutive alphabetic characters in upper or lower
case. Albert also wants your program to be case
insensitive, that is words like “APPLE”, “apple”,
“appLE” should be treated as the same.
Input
The input is a text with up to 5,000 lines. Each line
has at most 200 characters. The input if terminated
by EOF.
Output
A list of different/unique words that appear in the input text, one per line. You are guaranteed that the number of unique
words in the text is no more than 5,000.
Example 1
Input:
Albert has a dream: he wants to create his own dictionary (Merriam Webster is
his idol and he hopes to have his own name on a thick book one day).
Output:
a
albert
and
book
create
day
dictionary
dream
has
have
he
his
hopes
idol
is
merriam
name
on
one
own
thick
to
wants
webster
Page 2/2
Example 2
Input:
121()* &* abc *awre@#
Output:
abc
awre
Page 1/2
Ferry
Ferries used to carry cars across the
river. In your village, there is still a ferry
that can take up to N cars and needs
T minutes to cross the river. A car may
arrive at either river bank and wait to be
carried to the opposite bank. The ferry
operates continuously between the
banks as long it is carrying at least one
car or there is at least one car waiting on
either side. Whenever the ferry arrives at
one bank, it unloads cars carried and
loads up to N cars waiting at that bank.
When there are more than N cars
waiting, they are loaded on the firstcome-first-serve basis. If there is no car
waiting on either bank, the ferry stops
and waits until one car arrives. The ferry
is initially on the left bank. You are asked
to determine at what time each car
arrives at the other bank.
Input The first line of input contains
three integers N , T and M (
1 <= N, T, M <= 10,000 ). Each
of the following M lines gives the arrival
time of a car and the bank at which the
car arrives ( left or right ). The
cars are ordered by their arrival times (so the arrival times are non-decreasing) and the time spent on loading and unloading
can be ignored.
Output For each car, you should print one line containing one number, the time at which the car is unloaded at the opposite
bank.
Example 1
Input:
2 10 10
0 left
10 left
20 left
30 left
40 left
50 left
60 left
70 left
80 left
90 left
Output:
10
30
30
50
50
70
70
90
90
110
Page 2/2
Example 2
Input:
2 10 3
10 right
25 left
40 left
Output:
30
40
60
Page 1/1
Bit-wise OR
Given 3 non-negative integers N, L, R. Find the minimum integer x such that
1. L <= x <= R
2. x OR N is maximized (OR stands for bit-wise OR operation here), i.e. for all integers y in the close interval [L,R], we
have: (y OR N) <= (x OR N)
Input
There will be 3 integers N, L, R on a single line, where L <= R. You can assume that 0 <= N,L,R <= 4294967295.
Output
Print a line containing the value of x such that x OR N is maximized.
Example 1
Input:
10 10 10
Output:
10
Example 2
Input:
100 50 60
Output:
59
Page 1/1
Prime Gap
A prime gap is the difference between two successive prime numbers. The n-th prime gap, denoted g(n) is the difference
between the (n+1)-th and the n-th prime numbers, i.e.
g(n) = p(n+1) – p(n)
The first 7 prime numbers are 2, 3, 5, 7, 11, 13, 17, and the first 6 prime gaps are 1, 2, 2, 4, 2, 4.
Shinya Yukimura is interested in prime gaps and he need some experimental data to verify his hypothesis. More specifically,
given a closed interval [a,b], Shinya wants to find the two adjacent primes p1 and p2 (a <= p1 <= p2 <= b) such that the
prime gap between p1 and p2 is minimized (i.e. p2-p1 is the minimum). If there are multiple prime pairs that have the same
prime gap, report the first pair. Shinya also wants to find the two adjacent primes p3 and p4 (a <= p3 < p4 <= b) that
maximize the gap between p3 and p4 (choose the first pair if there are mote than one such pairs).
Please write a program to help Shinya.
Input
Two integer values a,b, with a < b. The difference between a and b will not exceed 1,000,000. 1 <= a <= b <=
2,147,483,647.
Output
If there are no adjacent primes in the interval [a,b], output -1 followed by a newline.
Otherwise the output should be 4 integers: p1 p2 p3 p4 as mentioned above separated by a space and followed by a
newline (no space after p4).
Example 1
Input:
1 20
Output:
2 3 7 11
Example 2
Input:
13 16
Output:
-1
In the first example test case, the prime gap between 13 and 17 also has the largest value 4, but the pair (7,11) appears
before (13,17), so we output 7 11 instead of 13 17.
