programming-examples/java/Data_Structures/HeavyLight2.java

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2019-11-15 12:59:38 +01:00
import java.util.*;
import java.util.stream.Stream;
public class HeavyLight2 {
// true - values on vertices, false - values on edges
static boolean VALUES_ON_VERTICES = true;
// Modify the following 6 methods to implement your custom operations on the tree.
// This example implements Add/Max operations. Operations like Add/Sum, Set/Max can also be implemented.
static int modifyOperation(int x, int y) {
return x + y;
}
// query (or combine) operation
static int queryOperation(int leftValue, int rightValue) {
return Math.max(leftValue, rightValue);
}
static int deltaEffectOnSegment(int delta, int segmentLength) {
if (delta == getNeutralDelta()) return getNeutralDelta();
// Here you must write a fast equivalent of following slow code:
// int result = delta;
// for (int i = 1; i < segmentLength; i++) result = queryOperation(result, delta);
// return result;
return delta;
}
static int getNeutralDelta() {
return 0;
}
static int getInitValue() {
return 0;
}
static int getNeutralValue() {
return Integer.MIN_VALUE;
}
// generic code
static int joinValueWithDelta(int value, int delta) {
if (delta == getNeutralDelta()) return value;
return modifyOperation(value, delta);
}
static int joinDeltas(int delta1, int delta2) {
if (delta1 == getNeutralDelta()) return delta2;
if (delta2 == getNeutralDelta()) return delta1;
return modifyOperation(delta1, delta2);
}
int[][] value;
int[][] delta; // delta[i] affects value[i], delta[2*i+1] and delta[2*i+2]
int[][] len;
List<Integer>[] tree;
int[] size;
int[] parent;
int[] tin;
int[] tout;
int time;
int[] path;
int[] pathSize;
int[] pathPos;
int[] pathRoot;
int pathCount;
public HeavyLight2(List<Integer>[] tree) {
this.tree = tree;
int n = tree.length;
size = new int[n];
parent = new int[n];
tin = new int[n];
tout = new int[n];
calcSizeParentTinTout(0, -1);
path = new int[n];
pathSize = new int[n];
pathPos = new int[n];
pathRoot = new int[n];
buildPaths(0, newPath(0));
value = new int[pathCount][];
delta = new int[pathCount][];
len = new int[pathCount][];
for (int i = 0; i < pathCount; i++) {
int m = pathSize[i];
value[i] = new int[2 * m];
for (int j = 0; j < m; j++)
value[i][j + m] = getInitValue();
for (int j = 2 * m - 1; j > 1; j -= 2)
value[i][j >> 1] = queryOperation(value[i][j], value[i][j ^ 1]);
delta[i] = new int[2 * m];
Arrays.fill(delta[i], getNeutralDelta());
len[i] = new int[2 * m];
Arrays.fill(len[i], m, 2 * m, 1);
for (int j = 2 * m - 1; j > 1; j -= 2)
len[i][j >> 1] = len[i][j] + len[i][j ^ 1];
}
}
void calcSizeParentTinTout(int u, int p) {
tin[u] = time++;
parent[u] = p;
size[u] = 1;
for (int v : tree[u])
if (v != p) {
calcSizeParentTinTout(v, u);
size[u] += size[v];
}
tout[u] = time++;
}
int newPath(int u) {
pathRoot[pathCount] = u;
return pathCount++;
}
void buildPaths(int u, int path) {
this.path[u] = path;
pathPos[u] = pathSize[path]++;
for (int v : tree[u]) {
if (v != parent[u])
buildPaths(v, 2 * size[v] >= size[u] ? path : newPath(v));
}
}
void pushDelta(int path, int i) {
int d = 0;
for (; (i >> d) > 0; d++)
;
for (d -= 2; d >= 0; d--) {
int x = i >> d;
value[path][x >> 1] = joinValueWithDelta0(path, x >> 1);
delta[path][x] = joinDeltas(delta[path][x], delta[path][x >> 1]);
delta[path][x ^ 1] = joinDeltas(delta[path][x ^ 1], delta[path][x >> 1]);
delta[path][x >> 1] = getNeutralDelta();
}
}
int joinValueWithDelta0(int path, int i) {
return joinValueWithDelta(value[path][i], deltaEffectOnSegment(delta[path][i], len[path][i]));
}
int queryPath(int path, int from, int to) {
from += value[path].length >> 1;
to += value[path].length >> 1;
pushDelta(path, from);
pushDelta(path, to);
int res = getNeutralValue();
for (; from <= to; from = (from + 1) >> 1, to = (to - 1) >> 1) {
if ((from & 1) != 0)
res = queryOperation(res, joinValueWithDelta0(path, from));
if ((to & 1) == 0)
res = queryOperation(res, joinValueWithDelta0(path, to));
}
return res;
}
void modifyPath(int path, int from, int to, int delta) {
from += value[path].length >> 1;
to += value[path].length >> 1;
pushDelta(path, from);
pushDelta(path, to);
int ta = -1;
int tb = -1;
for (; from <= to; from = (from + 1) >> 1, to = (to - 1) >> 1) {
if ((from & 1) != 0) {
this.delta[path][from] = joinDeltas(this.delta[path][from], delta);
if (ta == -1)
ta = from;
}
if ((to & 1) == 0) {
this.delta[path][to] = joinDeltas(this.delta[path][to], delta);
if (tb == -1)
tb = to;
}
}
for (int i = ta; i > 1; i >>= 1)
value[path][i >> 1] = queryOperation(joinValueWithDelta0(path, i), joinValueWithDelta0(path, i ^ 1));
for (int i = tb; i > 1; i >>= 1)
value[path][i >> 1] = queryOperation(joinValueWithDelta0(path, i), joinValueWithDelta0(path, i ^ 1));
}
boolean isAncestor(int p, int ch) {
return tin[p] <= tin[ch] && tout[ch] <= tout[p];
}
public int query(int a, int b) {
int res = getNeutralValue();
for (int root; !isAncestor(root = pathRoot[path[a]], b); a = parent[root])
res = queryOperation(res, queryPath(path[a], 0, pathPos[a]));
for (int root; !isAncestor(root = pathRoot[path[b]], a); b = parent[root])
res = queryOperation(res, queryPath(path[b], 0, pathPos[b]));
if (!VALUES_ON_VERTICES && a == b)
return res;
return queryOperation(
res,
queryPath(path[a], Math.min(pathPos[a], pathPos[b]) + (VALUES_ON_VERTICES ? 0 : 1),
Math.max(pathPos[a], pathPos[b])));
}
public void modify(int a, int b, int delta) {
for (int root; !isAncestor(root = pathRoot[path[a]], b); a = parent[root])
modifyPath(path[a], 0, pathPos[a], delta);
for (int root; !isAncestor(root = pathRoot[path[b]], a); b = parent[root])
modifyPath(path[b], 0, pathPos[b], delta);
if (!VALUES_ON_VERTICES && a == b)
return;
modifyPath(path[a], Math.min(pathPos[a], pathPos[b]) + (VALUES_ON_VERTICES ? 0 : 1),
Math.max(pathPos[a], pathPos[b]), delta);
}
// Random test
public static void main(String[] args) {
Random rnd = new Random(1);
VALUES_ON_VERTICES = true;
for (int step = 0; step < 1000; step++) {
int n = rnd.nextInt(50) + 1;
List<Integer>[] tree = getRandomTree(n, rnd);
int[] x = new int[n];
Arrays.fill(x, getInitValue());
HeavyLight2 hl = new HeavyLight2(tree);
for (int i = 0; i < 1000; i++) {
int a = rnd.nextInt(n);
int b = rnd.nextInt(n);
List<Integer> path = new ArrayList<>();
getPathFromAtoB(tree, a, b, -1, path);
if (rnd.nextBoolean()) {
int delta = rnd.nextInt(50) - 100;
hl.modify(a, b, delta);
for (int u : path)
x[u] = joinValueWithDelta(x[u], delta);
} else {
int res1 = hl.query(a, b);
int res2 = getNeutralValue();
for (int u : path)
res2 = queryOperation(res2, x[u]);
if (res1 != res2)
throw new RuntimeException();
}
}
}
VALUES_ON_VERTICES = false;
for (int step = 0; step < 1000; step++) {
int n = rnd.nextInt(50) + 1;
List<Integer>[] tree = getRandomTree(n, rnd);
Map<Long, Integer> x = new HashMap<>();
for (int u = 0; u < tree.length; u++)
for (int v : tree[u])
x.put(edge(u, v), getInitValue());
HeavyLight2 hl = new HeavyLight2(tree);
for (int i = 0; i < 1000; i++) {
int a = rnd.nextInt(n);
int b = rnd.nextInt(n);
List<Integer> path = new ArrayList<>();
getPathFromAtoB(tree, a, b, -1, path);
if (rnd.nextBoolean()) {
int delta = rnd.nextInt(50) - 100;
hl.modify(a, b, delta);
for (int j = 0; j + 1 < path.size(); j++) {
long key = edge(path.get(j), path.get(j + 1));
x.put(key, joinValueWithDelta(x.get(key), delta));
}
} else {
int res1 = hl.query(a, b);
int res2 = getNeutralValue();
for (int j = 0; j + 1 < path.size(); j++) {
long key = edge(path.get(j), path.get(j + 1));
res2 = queryOperation(res2, x.get(key));
}
if (res1 != res2)
throw new RuntimeException();
}
}
}
System.out.println("Test passed");
}
static long edge(int u, int v) {
return ((long) Math.min(u, v) << 16) + Math.max(u, v);
}
static boolean getPathFromAtoB(List<Integer>[] tree, int a, int b, int p, List<Integer> path) {
path.add(a);
if (a == b)
return true;
for (int u : tree[a])
if (u != p && getPathFromAtoB(tree, u, b, a, path))
return true;
path.remove(path.size() - 1);
return false;
}
static List<Integer>[] getRandomTree(int n, Random rnd) {
List<Integer>[] t = Stream.generate(ArrayList::new).limit(n).toArray(List[]::new);
int[] p = new int[n];
for (int i = 0, j; i < n; j = rnd.nextInt(i + 1), p[i] = p[j], p[j] = i, i++) ; // random permutation
for (int i = 1; i < n; i++) {
int parent = p[rnd.nextInt(i)];
t[parent].add(p[i]);
t[p[i]].add(parent);
}
return t;
}
}