Solution for Riddler Express 4/8/18

riddler_express_date_vandals.R

library(tidyverse)

month_vec <- c(rep(1, 31),
               rep(2, 28),
               rep(3, 31),
               rep(4, 30),
               rep(5, 31),
               rep(6, 30),
               rep(7, 31),
               rep(8, 31),
               rep(9, 30),
               rep(10, 31),
               rep(11, 30),
               rep(12, 31))
day_vec <- c(1:31,
             1:28,
             1:31,
             1:30,
             1:31,
             1:30,
             1:31,
             1:31,
             1:30,
             1:31,
             1:30,
             1:31)


century_dates <- tibble(month = rep(month_vec, 99),
       day = rep(day_vec, 99),
       year = rep(1:99, each = 365)) %>% 
  bind_rows(tibble(month = 2,
                   day = 29,
                   year = subset(1:99, 1:99 %% 4 == 0))) %>% 
  mutate(vandalism = ifelse(month*day==year, 1, 0),
         streak = 1) %>% 
  arrange(year, month, day)


sum(century_dates$vandalism)

century_dates %>% 
  group_by(year) %>% 
  summarize(year_vandalism = sum(vandalism)) %>% 
  arrange(-year_vandalism)

century_dates %>% 
  group_by(year) %>% 
  summarize(year_vandalism = sum(vandalism)) %>% 
  arrange(year_vandalism)

for (i in 2:length(century_dates$vandalism)){
  century_dates$streak[i] <- ifelse(century_dates$vandalism[i] == century_dates$vandalism[i-1], century_dates$streak[i-1] + 1, 1)
}

max(century_dates$streak)