[leetcode] Merge Intervals

import java.util.ArrayList;

import java.util.Collections;

import java.util.List;

/**

* Given a collection of intervals, merge all overlapping intervals.

For example,

Given [1,3],[2,6],[8,10],[15,18],

return [1,6],[8,10],[15,18].

*

*

* @author Chris

*

*/

class Interval implements Comparable<Interval>{

private int start;

private int end;

public Interval() {

}

public Interval(int start, int end) {

this.start = start;

this.end = end;

}

public void setStart(int start) {

this.start = start;

}

public void setEnd(int end) {

this.end = end;

}

public int getStart() {

return start;

}

public int getEnd() {

return end;

}

@Override

public String toString() {

return "Interval [start=" + start + ", end=" + end + "]";

}

@Override

public int compareTo(Interval o) {

return this.getStart() - o.getStart();

}

}

public class MergeIntervals {

static List<Interval> getMergeIntervals(List<Interval> intervals) {

if (intervals == null || intervals.size() == 0) {

return null;

}

List<Interval> result = new ArrayList<Interval>();

Collections.sort(intervals);

System.out.println(intervals);

Interval toAdd = intervals.get(0);

for (int i = 1; i < intervals.size(); i++) {

if(intervals.get(i).getStart() > toAdd.getEnd()) {

result.add(toAdd);

toAdd = intervals.get(i);

} else {

toAdd.setStart(toAdd.getStart());

int oldEnd = toAdd.getEnd();

toAdd.setEnd(Math.max(intervals.get(i).getEnd(), oldEnd));

}

}

if (toAdd != null) {

result.add(toAdd);

}

return result;

}

/**

* @param args

*/

public static void main(String[] args) {

List<Interval> intervals = new ArrayList<Interval>();

intervals.add(new Interval(1,3));

intervals.add(new Interval(8,10));

intervals.add(new Interval(15,18));

intervals.add(new Interval(2,6));

System.out.println("result = " + getMergeIntervals(intervals));

}

}