57. Insert Interval

Description

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].

Solution

/**
 * Definition for an interval.
 * function Interval(start, end) {
 *     this.start = start;
 *     this.end = end;
 * }
 */
/**
 * @param {Interval[]} intervals
 * @param {Interval} newInterval
 * @return {Interval[]}
 */
var insert = function(intervals, newInterval) {
    "use strict";
    let result = [];
    let pos = -2;
    for (let idx = 0; idx < intervals.length; idx++) {
        let interval = intervals[idx];
        // Push all intervals that are less than the start of the new interval
        if (newInterval.start > interval.end) {
            result.push(interval);
        }
        // Push all intervals that are greater than the end of the new interval
        if (interval.start > newInterval.end) {
            result.push(interval);
        }
        /* Find the inserted position */
        // The start of the new interval is less than the current interval
        if (newInterval.start < interval.start) {
            // If the inserted position has not been found
            if (pos === -2) {
                pos = idx;
            }
        }
        // The start of the new interval is within the current interval
        if (newInterval.start >= interval.start && newInterval.start <= interval.end) {
            newInterval.start = interval.start;
            // If inserted position has not been found
            if (pos === -2) {
                pos = idx;
            }
        }
        // The end of the new interval is within the current interval
        if (newInterval.end >= interval.start && newInterval.end <= interval.end) {
            newInterval.end = interval.end;
        }
    }
    // The new interval is less than all the intervals
    if (pos === -1) {
        result.splice(0, 0, newInterval);
    // The new interval is greater than all the intervals
    } else if (pos === -2) {
        result.splice(intervals.length, 0, newInterval);
    } else {
        result.splice(pos, 0, newInterval);
    }
    return result;
};