Solving with Ruby, Perl, Java, and Python AtCoder ARC 098 C Cumulative sum

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AtCoder Regular Contets C - Attention Difficulty: 641

This theme, cumulative sum Ruby Considering WEWEWEEEWWWE in input example 2, it becomes WEWEWEEiWWWE, and the total number of Ws on the left side of ʻi and the number of Es on the right side is the number of people to be calculated. From the left 0 to the right n-1 of the character string, ʻE is a monotonous decrease and W is a monotonous increase, so ** cumulative sum ** is used as a method to reduce the amount of calculation. ..

ruby.rb

n = gets.to_i
s = gets.chomp
e = (s[0] == 'E' ? [1] : [0])
w = (s[0] == 'W' ? [1] : [0])

1.upto(n - 1) do |i|
  if (s[i] == 'E')
    e[i] = e[i - 1] + 1
    w[i] = w[i - 1]
  else
    e[i] = e[i - 1]
    w[i] = w[i - 1] + 1
  end
end
w.unshift(0)
min = Float::INFINITY
0.upto(n - 1) do |i|
  min = e[-1] - e[i] + w[i] if min > e[-1] - e[i] + w[i]
end
puts min

sum.rb

1.upto(n - 1) do |i|
  if (s[i] == 'E')
    e[i] = e[i - 1] + 1
    w[i] = w[i - 1]
  else
    e[i] = e[i - 1]
    w[i] = w[i - 1] + 1
  end
end

The cumulative sum is calculated here.

inf.rb

min = Float::INFINITY

Infinity is set with Float :: INFINITY. Python

python.py

import sys

n = int(input())
s = input()
e = [0] * n
w = [0] * (n + 1)
e[0] = 1 if s[0] == 'E' else 0
w[0] = 0
w[1] = 1 if s[0] == 'W' else 0
for i in range(1, n):
    if s[i] == 'E':
        e[i] = e[i - 1] + 1
        w[i + 1] = w[i]
    else:
        e[i] = e[i - 1]
        w[i + 1] = w[i] + 1
min = sys.maxsize
for i in range(n):
    if min > e[-1] - e[i] + w[i]:
        min = e[-1] - e[i] + w[i]
print(min)

max.py

min = sys.maxsize

The upper limit of integers is set in sys.maxsize. Perl

perl.pl

chomp (my $n = <STDIN>);
chomp (my $s = <STDIN>);
my (@e, @w);
$e[0] = (substr($s, 0, 1) eq 'E' ? 1 : 0);
$w[0] = (substr($s, 0, 1) eq 'W' ? 1 : 0);
for my $i (1..$n-1) {
  if (substr($s, $i, 1) eq 'E') {
    $e[$i] = $e[$i - 1] + 1;
    $w[$i] = $w[$i - 1];
  } else {
    $e[$i] = $e[$i - 1];
    $w[$i] = $w[$i - 1] + 1;
  }
}
unshift @w, 0;
my $min = inf;
for my $i (0..$n-1) {
  $min = $e[-1] - $e[$i] + $w[$i] if $min > $e[-1] - $e[$i] + $w[$i];
}
print "$min\n";

inf.pl

my $min = inf;

Infinity is set with ʻinf`. Java

java.java

import java.util.*;

class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = Integer.parseInt(sc.next());
        char s[] = sc.next().toCharArray();
        sc.close();
        int e[] = new int[n];
        int w[] = new int[n + 1];
        w[0] = 0;
        if (s[0] == 'E') {
            e[0] = 1;
            w[1] = 0;
        } else {
            e[0] = 0;
            w[1] = 1;
        }
        for (int i = 1; i < n; i++) {
            if (s[i] == 'E') {
                e[i] = e[i - 1] + 1;
                w[i + 1] = w[i];
            } else {
                e[i] = e[i - 1];
                w[i + 1] = w[i] + 1;
            }
        }
        int min = Integer.MAX_VALUE;
        for (int i = 0; i < n; i++) {
            if (min > e[n - 1] - e[i] + w[i])
                min = e[n - 1] - e[i] + w[i];
        }
        System.out.println(min);
    }
}

inf.java

        int min = Integer.MAX_VALUE;

ʻInteger.MAX_VALUE` sets the maximum value of an integer.

Summary

• Solved ARC 098 C
• Become familiar with Ruby
• Become familiar with Python
• Become familiar with Perl
• Become familiar with Java

Referenced site

• I want to handle the maximum value of integers and the infinity of decimal numbers in Python3 *