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JavaScript

/**
 * Generate an array of timeslots based on timeinterval
 * Assumption for brevity: 
 * - startTime and endTime are of valid time
 * - startTime will never be later than end time
 * 
 * @param  {integer} timeinterval   In mins. Can only accept 15, 30 or 60
 * @param  {string}  startTime      '03:45'. Min - '00:00', Max - '24:00'
 * @param  {string}  endTime        '15:00'. Min - '00:00', Max - '24:00'
 * @return {array}                  ['03:45', ....., '15:00']
 */

function generateTimeslots(timeInterval, startTime, endTime) {
}