Arrange a DataStructure something like this.
Map
Where the keys could range practically from Day 1 to Day N. I have assumed the next 30 days and so the keys would range from Day1 to Day30.
Assume 10 Persons are required to book a meeting. And every one should be free on that slot for the meeting to be booked.
I have assumed 30 minute slots in a 8 hr work day. So there will be 16 slots in a day.
So for Day1-> You will be holding 10 Person's availability as a 10 by 16 2 dimensional int array/matrix. Each cell will either hold 0 or 1. 0 to indicate the person is not available and 1 to indicate he is available.
The key is to do an AND of each Person/Slot in pairs iteratively.
(Person1 availability on slot 0) & (Person2 availability on slot 0). If it is 0 break the loop immediately because we cannot find a match for this slot.
An exact match for a slot on a particular day is arrived at if the repeated ANDs yield 1 for a day/slot combo. I have attached my code below.
package com.ramesh.tests;
import java.util.Map;
import java.util.Random;
import java.util.TreeMap;
public class CalendarFinder {
public static void main(String[] args) {
int n=10 ;// no. of persons
int m=30 ;//no.of days
Map<String,int[][]> personCalendar = preparePersonCalendars(n,m);
printPersonCalendar(personCalendar);
Map<String,int[][]> testData = prepareTestData(n,m);
printPersonCalendar(testData);
meetingSlotFinder(testData);
meetingSlotFinder(personCalendar);
}
private static Map<String,int[][]> preparePersonCalendars(int n, int m) {
Random rnd = new Random();
Map<String,int[][]> personCalendar = new TreeMap<String,int[][]>();
for(int i=0; i<m; i++) { //iterate over days
int[][] daysSlots = new int[n][16];
for(int j=0;j<n;j++) { //iterate over persons
for(int slot=0;slot<16;slot++) {
daysSlots[j][slot] = rnd.nextInt(2);
}
}
personCalendar.put(i<9 ? "Day_0"+(i+1) : "Day_"+(i+1), daysSlots);
}
return personCalendar;
}
private static Map<String,int[][]> prepareTestData(int n, int m) {
Map<String,int[][]> testData = new TreeMap<String,int[][]>();
for(int i=0; i<m; i++) { //iterate over days
int[][] daysSlots = new int[n][16];
for(int j=0;j<n;j++) { //iterate over persons
for(int slot=0;slot<16;slot++) {
daysSlots[j][slot] = i%5==0 && slot%6==0 ? 1 : 0;
}
}
testData.put(i<9 ? "Day_0"+(i+1) : "Day_"+(i+1), daysSlots);
}
return testData;
}
private static void printPersonCalendar(Map<String,int[][]> personCalendar) {
for(Map.Entry<String, int[][]> calendar: personCalendar.entrySet()) {
System.out.println("Printing Calendar availability for : " + calendar.getKey());
int[][] pCalArray = calendar.getValue();
for(int i=0; i<pCalArray.length; i++) {
System.out.println("Person : " + (i+1));
for(int j=0;j<pCalArray[0].length;j++) {
System.out.print(" " + pCalArray[i][j]);
}
System.out.print("\r\n");
}
}
}
private static void meetingSlotFinder(Map<String,int[][]> personCalendar) {
int ctr=0;
for(Map.Entry<String, int[][]> calendar: personCalendar.entrySet()) {
int[][] pCalArray = calendar.getValue();
for(int j=0;j<pCalArray[0].length;j++) { // iterate over slots
int result = 1;
for(int i=0; i<pCalArray.length-1; i++) { //iterate over persons
ctr++;
result = result & pCalArray[i][j]& pCalArray[i+1][j];
if(result==0) break;
}
if(result == 1)
System.out.println("**** Meeting match at Day : " +
calendar.getKey() + " and at slot: " + j);
else
System.out.println("Couldn't find any meeting match at Day : " +
calendar.getKey() + " and at slot: " + j);
}
}
System.out.println("#@$&* Total Iterations performed : " + ctr);
}
}
