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77 lines
2.3 KiB
Java
77 lines
2.3 KiB
Java
import java.util.*;
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public class SegmentTree2D {
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public static int max(int[][] t, int x1, int y1, int x2, int y2) {
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int n = t.length >> 1;
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x1 += n;
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x2 += n;
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int m = t[0].length >> 1;
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y1 += m;
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y2 += m;
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int res = Integer.MIN_VALUE;
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for (int lx = x1, rx = x2; lx <= rx; lx = (lx + 1) >> 1, rx = (rx - 1) >> 1)
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for (int ly = y1, ry = y2; ly <= ry; ly = (ly + 1) >> 1, ry = (ry - 1) >> 1) {
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if ((lx & 1) != 0 && (ly & 1) != 0) res = Math.max(res, t[lx][ly]);
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if ((lx & 1) != 0 && (ry & 1) == 0) res = Math.max(res, t[lx][ry]);
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if ((rx & 1) == 0 && (ly & 1) != 0) res = Math.max(res, t[rx][ly]);
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if ((rx & 1) == 0 && (ry & 1) == 0) res = Math.max(res, t[rx][ry]);
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}
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return res;
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}
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public static void add(int[][] t, int x, int y, int value) {
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x += t.length >> 1;
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y += t[0].length >> 1;
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t[x][y] += value;
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for (int tx = x; tx > 0; tx >>= 1)
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for (int ty = y; ty > 0; ty >>= 1) {
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if (tx > 1) t[tx >> 1][ty] = Math.max(t[tx][ty], t[tx ^ 1][ty]);
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if (ty > 1) t[tx][ty >> 1] = Math.max(t[tx][ty], t[tx][ty ^ 1]);
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}
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// for (int ty = y; ty > 1; ty >>= 1)
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// t[x][ty >> 1] = Math.max(t[x][ty], t[x][ty ^ 1]);
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// for (int tx = x; tx > 1; tx >>= 1)
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// for (int ty = y; ty > 0; ty >>= 1)
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// t[tx >> 1][ty] = Math.max(t[tx][ty], t[tx ^ 1][ty]);
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// for (int lx=x; lx> 0; lx >>= 1) {
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// if (lx > 1)
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// t[lx >> 1][y] = Math.max(t[lx][y], t[lx ^ 1][y]);
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// for (int ly = y; ly > 1; ly >>= 1)
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// t[lx][ly >> 1] = Math.max(t[lx][ly], t[lx][ly ^ 1]);
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// }
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}
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public static void main(String[] args) {
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Random rnd = new Random(1);
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for (int step1 = 0; step1 < 1000; step1++) {
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int sx = rnd.nextInt(10) + 1;
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int sy = rnd.nextInt(10) + 1;
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int[][] t = new int[sx * 2][sy * 2];
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int[][] tt = new int[sx][sy];
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for (int step2 = 0; step2 < 1000; step2++) {
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if (rnd.nextBoolean()) {
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int x = rnd.nextInt(sx);
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int y = rnd.nextInt(sy);
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int v = rnd.nextInt(10) - 5;
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add(t, x, y, v);
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tt[x][y] += v;
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} else {
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int x2 = rnd.nextInt(sx);
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int x1 = rnd.nextInt(x2 + 1);
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int y2 = rnd.nextInt(sy);
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int y1 = rnd.nextInt(y2 + 1);
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int res1 = max(t, x1, y1, x2, y2);
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int res2 = Integer.MIN_VALUE;
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for (int x = x1; x <= x2; x++)
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for (int y = y1; y <= y2; y++)
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res2 = Math.max(res2, tt[x][y]);
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if (res1 != res2)
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throw new RuntimeException();
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}
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}
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}
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}
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}
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