_57.java

package com.fishercoder.solutions;

import com.fishercoder.common.classes.Interval;

import java.util.ArrayList;
import java.util.List;

/**
 * 57. Insert Interval
 *
 * Given a set of non-overlapping intervals, insert a new interval into the intervals (merge if necessary).

 You may assume that the intervals were initially sorted according to their start times.

 Example 1:
 Given intervals [1,3],[6,9], insert and merge [2,5] in as [1,5],[6,9].

 Example 2:
 Given [1,2],[3,5],[6,7],[8,10],[12,16], insert and merge [4,9] in as [1,2],[3,10],[12,16].

 This is because the new interval [4,9] overlaps with [3,5],[6,7],[8,10].
 */
public class _57 {

  public static class Solution1 {
    public List<Interval> insert(List<Interval> intervals, Interval newInterval) {
      List<Interval> result = new ArrayList<>();
      int i = 0;
      // add all the intervals ending before newInterval starts
      while (i < intervals.size() && intervals.get(i).end < newInterval.start) {
        result.add(intervals.get(i++));
      }
      // merge all overlapping intervals to one considering newInterval
      while (i < intervals.size() && intervals.get(i).start <= newInterval.end) {
        newInterval = new Interval( // we could mutate newInterval here also
            Math.min(newInterval.start, intervals.get(i).start),
            Math.max(newInterval.end, intervals.get(i).end));
        i++;
      }
      result.add(newInterval);
      // add all the rest
      while (i < intervals.size()) {
        result.add(intervals.get(i++));
      }
      return result;
    }
  }
}