split-sum.zsh

#!/bin/zsh

splitSum() {
    nums=("$@")
    totalLeft=0
    totalRight=0
    left=1
    right=$#

    if [[ $right -lt 2 ]]; then
      echo '" " " "'
      return
    fi

    while [[ $right -ne $left ]]; do
      if [[ "$totalLeft" -le "$totalRight" ]]; then
        totalLeft=$(($totalLeft + ${nums[$left]}))
        left=$(($left + 1))
      else
        totalRight=$(($totalRight + ${nums[$right]}))
        right=$(($right - 1))
      fi
    done

    # Check middle in the left group.
    if [ $(($totalLeft + ${nums[$left]})) -eq $totalRight ]; then
      leftArray=("${nums[@]:1:$left}")
      rightArray=("${nums[@]:$right}")
      echo "\"${leftArray[@]}\" \"${rightArray[@]}\""
      return
    fi
    # Check middle in the right group.
    if [[ $totalLeft -eq $(($totalRight + ${nums[$right]})) ]]; then
      leftArray=("${nums[@]:1:$((left - 1))}")
      rightArray=("${nums[@]:$((right - 1))}")
      echo "\"${leftArray[@]}\" \"${rightArray[@]}\""
      return
    fi
    echo '" " " "'
    return
}

# Global so they aren't reallcoated on the stack each invocation.
cases=(" " \
       "100" \
       "99 99" \
       "98 1 99" \
       "99 1 98" \
       "1 2 3 0" \
       "1 2 3 5" \
       "1 2 2 1 0" \
       "10 11 12 16 17" \
       "1 1 1 1 1 1 6" \
       "6 1 1 1 1 1 1" \
      )

# Test cases
testCases() {
    toScreen=("$@")

    for c in ${cases[@]}; do
        if [[ -z "$toScreen" ]]; then
            splitSum ${=c} > /dev/null
        else
            echo "zsh: \"$c\" -> $(splitSum ${=c})"
        fi
    done
}

testCases "true"

start_time=$(date +%s)

# zsh is so slow, do 100,000 then * 10
for ((i = 0; i < 100000; i++)); do
    testCases
done

end_time=$(date +%s)
elapsed_time=$((end_time - start_time))
elapsed_time=$((elapsed_time * 10))
echo "zsh: $elapsed_time seconds"