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package class31;
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import java.util.ArrayList;
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import java.util.HashMap;
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import java.util.List;
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import java.util.TreeSet;
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public class Code02_FallingSquares {
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public static class SegmentTree {
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private int[] max;
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private int[] change;
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private boolean[] update;
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public SegmentTree(int size) {
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int N = size + 1;
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max = new int[N << 2];
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change = new int[N << 2];
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update = new boolean[N << 2];
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}
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private void pushUp(int rt) {
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max[rt] = Math.max(max[rt << 1], max[rt << 1 | 1]);
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}
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// ln表示左子树元素结点个数，rn表示右子树结点个数
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private void pushDown(int rt, int ln, int rn) {
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if (update[rt]) {
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update[rt << 1] = true;
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update[rt << 1 | 1] = true;
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change[rt << 1] = change[rt];
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change[rt << 1 | 1] = change[rt];
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max[rt << 1] = change[rt];
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max[rt << 1 | 1] = change[rt];
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update[rt] = false;
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}
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}
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public void update(int L, int R, int C, int l, int r, int rt) {
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if (L <= l && r <= R) {
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update[rt] = true;
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change[rt] = C;
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max[rt] = C;
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return;
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}
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int mid = (l + r) >> 1;
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pushDown(rt, mid - l + 1, r - mid);
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if (L <= mid) {
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update(L, R, C, l, mid, rt << 1);
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}
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if (R > mid) {
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update(L, R, C, mid + 1, r, rt << 1 | 1);
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}
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pushUp(rt);
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}
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public int query(int L, int R, int l, int r, int rt) {
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if (L <= l && r <= R) {
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return max[rt];
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}
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int mid = (l + r) >> 1;
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pushDown(rt, mid - l + 1, r - mid);
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int left = 0;
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int right = 0;
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if (L <= mid) {
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left = query(L, R, l, mid, rt << 1);
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}
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if (R > mid) {
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right = query(L, R, mid + 1, r, rt << 1 | 1);
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}
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return Math.max(left, right);
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}
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}
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public HashMap<Integer, Integer> index(int[][] positions) {
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TreeSet<Integer> pos = new TreeSet<>();
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for (int[] arr : positions) {
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pos.add(arr[0]);
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pos.add(arr[0] + arr[1] - 1);
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}
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HashMap<Integer, Integer> map = new HashMap<>();
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int count = 0;
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for (Integer index : pos) {
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map.put(index, ++count);
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}
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return map;
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}
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public List<Integer> fallingSquares(int[][] positions) {
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HashMap<Integer, Integer> map = index(positions);
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int N = map.size();
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SegmentTree segmentTree = new SegmentTree(N);
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int max = 0;
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List<Integer> res = new ArrayList<>();
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// 每落一个正方形，收集一下，所有东西组成的图像，最高高度是什么
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for (int[] arr : positions) {
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int L = map.get(arr[0]);
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int R = map.get(arr[0] + arr[1] - 1);
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int height = segmentTree.query(L, R, 1, N, 1) + arr[1];
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max = Math.max(max, height);
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res.add(max);
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segmentTree.update(L, R, height, 1, N, 1);
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}
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return res;
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}
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}
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