ข้อ 2

<?php 
// 64160267 kanokpol promtha 
// DiagonalDifference
function exam02($arry){
    $arrDiag = count($arry);
    //ซ้าย
    $firstD = 0;
    // ขวา
    $secondD = 0;
    $i = 0;
    for($j = 0; $j < $arrDiag; $j++){
        $firstD += $arry[$i++][$j];
        $secondD += $arry[$arrDiag - $i][$j];
    }
    // ซ่าย - ขวา
    return abs($firstD - $secondD);
}

function test_01(){
    if(exam02([[1,2],[3,4]]) == 0){
        echo "pass";
    } else {
        echo "fail";
    }
    if(exam02([[1,2,4],
              [4,5,9],
              [7,8,9]]) == 1){
        echo "pass";
    } else {
        echo "fail";
    }
}

test_01();