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Find a pair of elements from an array whose sum equals a given number
... its index.
hash(arr[i]) = i
end-for
for i=0 to arr.length - 1 do
# if K-th element exists and it's different then we found a pair
if hash(K - arr[i]) != i
print "pair i , hash(K - arr[i]) has sum K"
end-if
end-for
...
Bash: If/Else statement in one line
I am trying to check if a process (assume it is called some_process ) is running on a server. If it is, then echo 1, otherwise echo 0.
...
Implicit type conversion rules in C++ operators
...C++ operators (for POD types) always act on objects of the same type.
Thus if they are not the same one will be promoted to match the other.
The type of the result of the operation is the same as operands (after conversion).
If either is long double the other is promoted to long...
How to convert number to words in java
...= {
"",
" ten",
" twenty",
" thirty",
" forty",
" fifty",
" sixty",
" seventy",
" eighty",
" ninety"
};
private static final String[] numNames = {
"",
" one",
" two",
" three",
" four",
" five",
" six",
" seven",
" eigh...
Catching error codes in a shell pipe
...
If you really don't want the second command to proceed until the first is known to be successful, then you probably need to use temporary files. The simple version of that is:
tmp=${TMPDIR:-/tmp}/mine.$$
if ./a > $tmp.1
...
How to open, read, and write from serial port in C?
...o-out a struct termios, configure it, and then set the tty with tcsetattr. If you use the zero-out method, then you will experience unexplained intermittent failures, especially on the BSDs and OS X. "Unexplained intermittent failures" include hanging in read(3).
#include <errno.h>
#include &...
Simulate CREATE DATABASE IF NOT EXISTS for PostgreSQL?
... not exist through JDBC. Unlike MySQL, PostgreSQL does not support create if not exists syntax. What is the best way to accomplish this?
...
How can I check if a single character appears in a string?
...
You can use string.indexOf('a').
If the char a is present in string :
it returns the the index of the first occurrence of the character in
the character sequence represented by this object, or -1 if the
character does not occur.
...
Checking if a key exists in a JavaScript object?
How do I check if a particular key exists in a JavaScript object or array?
22 Answers
...
python dataframe pandas drop column using int
... index like this:
df.drop(df.columns[i], axis=1)
It could work strange, if you have duplicate names in columns, so to do this you can rename column you want to delete column by new name. Or you can reassign DataFrame like this:
df = df.iloc[:, [j for j, c in enumerate(df.columns) if j != i]]
...