Filtering a vector on condition

unique(Reduce(function(x,y)ifelse(y-x>=100,y,x),input,accumulate = T))
[1]  24 128 228 356 532 634 839 997

Not thoroughly tested, but I believe this gets you there. I am using purrr::accumulate. This is a pretty neat problem :-) hoping to see some other solutions/approaches, so maybe leave this open (unanswered) for a bit...

library(purrr)

input <- c(24, 49, 74, 128, 146, 153, 165, 228, 303, 321, 356, 410, 532, 561, 601, 622, 634, 839, 882, 997)
idx <- which(accumulate(diff(input), ~ ifelse(.x >= 100, .y, .x + .y)) >= 100)
input[c(1, idx + 1)]
#> [1]  24 128 228 356 532 634 839 997

And to make this read a little more purrr, I suppose we could do:

accumulate(diff(input), ~ if_else(.x >= 100, .y, .x + .y)) %>%
  map_lgl(~ . >= 100) %>%
  which %>%
  { input[c(1, . + 1)] }