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| class Solution {
private static class UnionFind{
private final int[] parent;
public UnionFind(int n) {
this.parent = new int[n];
for (int i = 0; i < n; i++) {
parent[i] = i;
}
}
public void union(int x, int y) {
int xRoot = getRoot(x), yRoot = getRoot(y);
if (xRoot == yRoot) {
return;
}
parent[xRoot] = yRoot;
}
private int getRoot(int x) {
if (x != parent[x]) {
int root = getRoot(parent[x]);
parent[x] = root;
}
return parent[x];
}
public boolean isConnected(int x, int y) {
return getRoot(x) == getRoot(y);
}
}
private static class Point {
private final int i;
private final int j;
public Point(int i, int j) {
this.i = i;
this.j = j;
}
}
private static class Edge {
private final Point a;
private final Point b;
private final int weight;
public Edge(Point a, Point b, int weight) {
this.a = a;
this.b = b;
this.weight = weight;
}
}
public int minimumEffortPath(int[][] heights) {
int m = heights.length, n = heights[0].length;
List<Edge> edgeList = new ArrayList<>();
for (int i = 0; i < m; i++) {
for (int j = 0; j < n; j++) {
Point a = new Point(i, j);
if (j + 1 < n) {
edgeList.add(new Edge(a, new Point(i, j + 1), Math.abs(heights[i][j + 1] - heights[i][j])));
}
if (i + 1 < m) {
edgeList.add(new Edge(a, new Point(i + 1, j), Math.abs(heights[i + 1][j] - heights[i][j])));
}
}
}
edgeList.sort(Comparator.comparingInt(o -> o.weight));
UnionFind unionFind = new UnionFind(m * n);
Point startPoint = new Point(0, 0), endPoint = new Point(m - 1, n - 1);
for (Edge edge : edgeList) {
unionFind.union(getIndex(n, edge.a), getIndex(n, edge.b));
if (unionFind.isConnected(getIndex(n, startPoint), getIndex(n, endPoint))) {
return edge.weight;
}
}
return 0;
}
private int getIndex(int n, Point point) {
return point.i * n + point.j;
}
}
|