Is BASH very slow?

Question

I was solving this question on SPOJ - http://www.spoj.com/problems/ALICESIE/

What the question boils down to print (n+1)/2

This is my C code which passes in

Answer 1

Bash is slower than C, for sure, because of the reasons given in other answers, but that doesn't explain what's happening here. I suspect you're letting one of your reads hang forever, until timeout. When I implement this:

#!/bin/bash

main() {
    local test
    local i
    local n
    read test
    for (( i=$test; i>0; i--)); do
        read n
        echo "$(((n+1)/2))"
    done
}

time {
    echo 1000
    printf '%d\n' {1002..2}
} | main

It doesn't take very much time:

real    0m0.033s
user    0m0.029s
sys 0m0.013s

You can force the read statements to time out on their own with the -t flag to read, like this:

main() {
    local test
    local i
    local n
    read -t.3 test
    if [[ -z $test ]]; then
        echo "Failed to read a test value within 300ms."
        return 1
    }
    for (( i=$test; i>0; i--)); do
        read -t.3 n
        if [[ -z $n ]]; then
            echo "Failed to read a value for n within 300ms."
            return 1
        }
        echo "$(((n+1)/2))"
    done
}