solution to https://amazon.interviewstreet.com/challenges/dashboard/#problem/4fd651016cd04

Schedule.java

import java.io.*;
import java.util.*;
public class Schedule {
	public static void main(String args[]) throws IOException{
		BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
		StringTokenizer st=new StringTokenizer(br.readLine());
		boolean m[]=new boolean[1441];m[1440]=false;
		int n=Integer.parseInt(st.nextToken());int meeting_time=Integer.parseInt(st.nextToken()),shh,smm,ehh,emm,ashh=0,asmm=0,aehh=0,aemm=0;
		while(n--!=0){
			st=new StringTokenizer(br.readLine());
			shh=Integer.parseInt(st.nextToken());smm=Integer.parseInt(st.nextToken());ehh=Integer.parseInt(st.nextToken());emm=Integer.parseInt(st.nextToken());
			if(emm==0){emm=59;ehh-=1;}
			else emm--;
			for(int i=shh*60+smm;i<=ehh*60+emm;i++){
				m[i]=true;
			}
		}
		int curr_run=0,flag=0;;
		for(int i=0;i<=1440;i++){
			if(m[i]==false) {
				if(curr_run==0){
					asmm=i%60;
					ashh=(i-asmm)/60;
				}
				curr_run++;
			}	
			else {
				if(curr_run>=meeting_time){
					aemm=i%60;
					aehh=(i-aemm)/60;
					System.out.format("%02d %02d %02d %02d\n",ashh,asmm,aehh,aemm);
				}
				curr_run=0; 
				}
		}
		if(curr_run>=meeting_time){
			aemm=00;
			aehh=00;
			System.out.format("%02d %02d %02d %02d\n",ashh,asmm,aehh,aemm);
		}
	}
}