diff options
author | Haidong Ji | 2018-09-26 20:55:07 -0500 |
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committer | Haidong Ji | 2018-09-26 20:55:07 -0500 |
commit | 9d38fc09a4cd5a1b187b77b8f62768a2e59752de (patch) | |
tree | efadb6d19d40a4586c4e268fb642b6d1a08cd372 /AlgoDesignAndTechniqueEdxJava/sources | |
parent | 68cad41492dc546c7f9a5459c991892d5b01abca (diff) |
Covering Segments done!
Pretty challenging and interesting. I'm glad I worked out the algo in
Python first for this problem. Good review of the comparable interface.
Good feeling of stream and lambda functions. Eclipse's erronous
reporting of errors is annoying.
Diffstat (limited to 'AlgoDesignAndTechniqueEdxJava/sources')
-rw-r--r-- | AlgoDesignAndTechniqueEdxJava/sources/CoveringSegments.java | 42 |
1 files changed, 28 insertions, 14 deletions
diff --git a/AlgoDesignAndTechniqueEdxJava/sources/CoveringSegments.java b/AlgoDesignAndTechniqueEdxJava/sources/CoveringSegments.java index db92e1f..8cad411 100644 --- a/AlgoDesignAndTechniqueEdxJava/sources/CoveringSegments.java +++ b/AlgoDesignAndTechniqueEdxJava/sources/CoveringSegments.java @@ -48,39 +48,53 @@ public class CoveringSegments { } public static void main(String[] args) { +// Scanner scanner = new Scanner(System.in); +// int n = scanner.nextInt(); +// Set<Segment> segments = new HashSet<Segment>(); +// for (int i = 0; i < n; i++) { +// int start, end; +// start = scanner.nextInt(); +// end = scanner.nextInt(); +// segments.add(new Segment(start, end)); +// } +// Segment[] s = segments.stream().toArray(Segment[]::new); +// Arrays.sort(s); +// int[] points = getOptimalPoints(s); +// System.out.println(points.length); +// for (int point : points) { +// System.out.print(point + " "); +// } Scanner scanner = new Scanner(System.in); int n = scanner.nextInt(); - Set<Segment> segments = new HashSet<Segment>(); + Segment[] segments = new Segment[n]; for (int i = 0; i < n; i++) { int start, end; start = scanner.nextInt(); end = scanner.nextInt(); - segments.add(new Segment(start, end)); + segments[i] = new Segment(start, end); } - Segment[] s = segments.stream().toArray(Segment[]::new); - Arrays.sort(s); - Integer[] points = getOptimalPoints(s); + Set<Segment> s = new HashSet<Segment>(Arrays.asList(segments)); + Segment[] newArray = s.stream().toArray(Segment[]::new); + Arrays.sort(newArray); + int[] points = getOptimalPoints(newArray); System.out.println(points.length); for (int point : points) { System.out.print(point + " "); } } - public static Integer[] getOptimalPoints(Segment[] s) { + public static int[] getOptimalPoints(Segment[] s) { int index = 0; List<Integer> points = new ArrayList<Integer>(); while (index < s.length) { points.add(s[index].end); - index++; - int temp = (int) points.get(points.size()-1); - while (index < s.length && s[index].start <= temp) { - if (s[index].end < temp) + index = index + 1; + while (index < s.length && s[index].start <= points.get(points.size()-1).intValue()) { + if (s[index].end < points.get(points.size()-1).intValue()) points.set(points.size()-1, s[index].end); - index++; + index = index + 1; } } - Integer[] results = new Integer[points.size()]; - results = points.toArray(results); - return results; + return points.stream().mapToInt(i -> i).toArray(); } } |