Question

How to check if the last index of an array is reachable by jumping based on element values from index 0 in PHP

Answer 1

function canReachLastIndex(array $arr): bool {
    $size = count($arr);
    $currentIndex = 0;

    while ($currentIndex < $size) {
        // If we reach the last index, return true
        if ($currentIndex == $size - 1) {
            return true;
        }

        // If jump goes out of bounds, stop
        if ($currentIndex + $arr[$currentIndex] >= $size) {
            return false;
        }

        // Move to the next index by jumping
        $currentIndex += $arr[$currentIndex];
    }

    return false;
}

function main() {
    $arr = [2, 3, 1, 1, 4];

    if (canReachLastIndex($arr)) {
        echo "Yes, we can reach the last index.\n";
    } else {
        echo "No, we cannot reach the last index.\n";
    }
}

main();



/*
run:

Yes, we can reach the last index.

*/

 

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