Description:
------------
if time is 00:00am to 00:59am 
or 00:00pm to 00:59pm 
strtotime()


Test script:
---------------
<?php
    $time1 = '5:20am';
    $time2 = '12:55pm';
    $time3 = '9:55pm';
    $time4 = '0:45pm';


    $date = date('Y-m-d');
    echo date('Y-m-d H:i:s',strtotime($date.$time1)).PHP_EOL;
    echo date('Y-m-d H:i:s',strtotime($date.$time2)).PHP_EOL;
    echo date('Y-m-d H:i:s',strtotime($date.$time3)).PHP_EOL;
    echo date('Y-m-d H:i:s',strtotime($date.$time4)).PHP_EOL;


?>



2017-03-20 05:20:00
2017-03-20 12:55:00
2017-03-20 21:55:00
1970-01-01 08:00:00

Expected result:
----------------
<?php
    $time1 = '5:20am';
    $time2 = '12:55pm';
    $time3 = '9:55pm';
    $time4 = '0:45pm';


    $date = date('Y-m-d');
    echo date('Y-m-d H:i:s',strtotime($date.$time1)).PHP_EOL;
    echo date('Y-m-d H:i:s',strtotime($date.$time2)).PHP_EOL;
    echo date('Y-m-d H:i:s',strtotime($date.$time3)).PHP_EOL;
    echo date('Y-m-d H:i:s',strtotime($date.$time4)).PHP_EOL;


?>

Actual result:
--------------
2017-03-20 05:20:00
2017-03-20 12:55:00
2017-03-20 21:55:00
1970-01-01 08:00:00