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74 lines
2.0 KiB
74 lines
2.0 KiB
package class04;
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import java.util.ArrayList;
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import java.util.Arrays;
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import java.util.Comparator;
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import java.util.List;
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import java.util.Map.Entry;
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import java.util.TreeMap;
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// 本题测试链接 : https://leetcode.com/problems/the-skyline-problem/
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public class Code08_TheSkylineProblem {
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public static class Node {
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public int x;
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public boolean isAdd;
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public int h;
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public Node(int x, boolean isAdd, int h) {
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this.x = x;
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this.isAdd = isAdd;
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this.h = h;
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}
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}
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public static class NodeComparator implements Comparator<Node> {
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@Override
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public int compare(Node o1, Node o2) {
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return o1.x - o2.x;
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}
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}
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public static List<List<Integer>> getSkyline(int[][] matrix) {
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Node[] nodes = new Node[matrix.length * 2];
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for (int i = 0; i < matrix.length; i++) {
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nodes[i * 2] = new Node(matrix[i][0], true, matrix[i][2]);
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nodes[i * 2 + 1] = new Node(matrix[i][1], false, matrix[i][2]);
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}
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Arrays.sort(nodes, new NodeComparator());
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// key 高度 value 次数
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TreeMap<Integer, Integer> mapHeightTimes = new TreeMap<>();
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TreeMap<Integer, Integer> mapXHeight = new TreeMap<>();
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for (int i = 0; i < nodes.length; i++) {
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if (nodes[i].isAdd) {
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if (!mapHeightTimes.containsKey(nodes[i].h)) {
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mapHeightTimes.put(nodes[i].h, 1);
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} else {
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mapHeightTimes.put(nodes[i].h, mapHeightTimes.get(nodes[i].h) + 1);
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}
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} else {
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if (mapHeightTimes.get(nodes[i].h) == 1) {
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mapHeightTimes.remove(nodes[i].h);
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} else {
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mapHeightTimes.put(nodes[i].h, mapHeightTimes.get(nodes[i].h) - 1);
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}
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}
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if (mapHeightTimes.isEmpty()) {
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mapXHeight.put(nodes[i].x, 0);
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} else {
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mapXHeight.put(nodes[i].x, mapHeightTimes.lastKey());
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}
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}
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List<List<Integer>> ans = new ArrayList<>();
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for (Entry<Integer, Integer> entry : mapXHeight.entrySet()) {
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int curX = entry.getKey();
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int curMaxHeight = entry.getValue();
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if (ans.isEmpty() || ans.get(ans.size() - 1).get(1) != curMaxHeight) {
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ans.add(new ArrayList<>(Arrays.asList(curX, curMaxHeight)));
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}
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}
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return ans;
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}
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}
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