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algorithmbasic2020
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add problems about UnionFind

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pull/6/head
左程云 4 years ago
parent f7f20b40d1
commit 5cf6403b9c
3 changed files with 270 additions and 45 deletions
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69
src/class09_15/Code01_FriendCircles.java
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@ -0,0 +1,69 @@
package class09_15;
// 本题为leetcode原题
// 测试链接：https://leetcode.com/problems/friend-circles/
// 可以直接通过
public class Code01_FriendCircles {
public static class UnionFind {
private int[] parent;
private int[] size;
private int[] help;
private int sets;
public UnionFind(int N) {
parent = new int[N];
size = new int[N];
help = new int[N];
sets = N;
for (int i = 0; i < N; i++) {
parent[i] = i;
size[i] = 1;
}
}
private int find(int i) {
int hi = 0;
while (i != parent[i]) {
help[hi++] = i;
i = parent[i];
}
for (hi--; hi >= 0; hi--) {
parent[help[hi]] = i;
}
return i;
}
public void union(int i, int j) {
int f1 = find(i);
int f2 = find(j);
if (f1 != f2) {
if (size[f1] >= size[f2]) {
size[f1] += size[f2];
parent[f2] = f1;
} else {
size[f2] += size[f1];
parent[f1] = f2;
}
sets--;
}
}
public int sets() {
return sets;
}
}
public static int findCircleNum(int[][] M) {
int N = M.length;
UnionFind unionFind = new UnionFind(N);
for (int i = 0; i < N; i++) {
for (int j = i + 1; j < N; j++) {
if (M[i][j] == 1) {
unionFind.union(i, j);
}
}
}
return unionFind.sets();
}
}

152
src/class09_14/Code06_IslandProblem.java → src/class09_15/Code02_NumberOfIslands.java
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@ -1,17 +1,17 @@
package class09_14;
package class09_15;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Stack;
import class09_14.Code05_UnionFind.UnionSet;
public class Code02_NumberOfIslands {
public class Code06_IslandProblem {
public static int solve1(int[][] board) {
public static int numIslands3(char[][] board) {
int islands = 0;
for (int i = 0; i < board.length; i++) {
for (int j = 0; j < board[0].length; j++) {
if (board[i][j] == 1) {
if (board[i][j] == '1') {
islands++;
infect(board, i, j);
}
@ -20,81 +20,140 @@ public class Code06_IslandProblem {
return islands;
}
public static void infect(int[][] board, int i, int j) {
if (i < 0 || i == board.length || j < 0 || j == board[0].length || board[i][j] != 1) {
public static void infect(char[][] board, int i, int j) {
if (i < 0 || i == board.length || j < 0 || j == board[0].length || board[i][j] != '1') {
return;
}
board[i][j] = 2;
board[i][j] = 0;
infect(board, i - 1, j);
infect(board, i + 1, j);
infect(board, i, j - 1);
infect(board, i, j + 1);
}
public static int solve2(int[][] board) {
public static int numIslands1(char[][] board) {
int row = board.length;
int col = board[0].length;
Dot[][] dots = new Dot[row][col];
List<Dot> dotList = new ArrayList<>();
for (int i = 0; i < row; i++) {
for (int j = 0; j < col; j++) {
if (board[i][j] == 1) {
if (board[i][j] == '1') {
dots[i][j] = new Dot();
dotList.add(dots[i][j]);
}
}
}
UnionSet<Dot> us = new UnionSet<>(dotList);
UnionFind1<Dot> uf = new UnionFind1<>(dotList);
for (int j = 1; j < col; j++) {
if (board[0][j - 1] == 1 && board[0][j] == 1) {
us.union(dots[0][j - 1], dots[0][j]);
if (board[0][j - 1] == '1' && board[0][j] == '1') {
uf.union(dots[0][j - 1], dots[0][j]);
}
}
for (int i = 1; i < row; i++) {
if (board[i - 1][0] == 1 && board[i][0] == 1) {
us.union(dots[i - 1][0], dots[i][0]);
if (board[i - 1][0] == '1' && board[i][0] == '1') {
uf.union(dots[i - 1][0], dots[i][0]);
}
}
for (int i = 1; i < row; i++) {
for (int j = 1; j < col; j++) {
if (board[i][j] == 1) {
if (board[i][j - 1] == 1) {
us.union(dots[i][j - 1], dots[i][j]);
if (board[i][j] == '1') {
if (board[i][j - 1] == '1') {
uf.union(dots[i][j - 1], dots[i][j]);
}
if (board[i - 1][j] == 1) {
us.union(dots[i - 1][j], dots[i][j]);
if (board[i - 1][j] == '1') {
uf.union(dots[i - 1][j], dots[i][j]);
}
}
}
}
return us.sets();
return uf.sets();
}
public static class Dot {
}
public static int solve3(int[][] board) {
public static class Node<V> {
V value;
public Node(V v) {
value = v;
}
}
public static class UnionFind1<V> {
public HashMap<V, Node<V>> nodes;
public HashMap<Node<V>, Node<V>> parents;
public HashMap<Node<V>, Integer> sizeMap;
public UnionFind1(List<V> values) {
nodes = new HashMap<>();
parents = new HashMap<>();
sizeMap = new HashMap<>();
for (V cur : values) {
Node<V> node = new Node<>(cur);
nodes.put(cur, node);
parents.put(node, node);
sizeMap.put(node, 1);
}
}
public Node<V> findFather(Node<V> cur) {
Stack<Node<V>> path = new Stack<>();
while (cur != parents.get(cur)) {
path.push(cur);
cur = parents.get(cur);
}
while (!path.isEmpty()) {
parents.put(path.pop(), cur);
}
return cur;
}
public void union(V a, V b) {
Node<V> aHead = findFather(nodes.get(a));
Node<V> bHead = findFather(nodes.get(b));
if (aHead != bHead) {
int aSetSize = sizeMap.get(aHead);
int bSetSize = sizeMap.get(bHead);
Node<V> big = aSetSize >= bSetSize ? aHead : bHead;
Node<V> small = big == aHead ? bHead : aHead;
parents.put(small, big);
sizeMap.put(big, aSetSize + bSetSize);
sizeMap.remove(small);
}
}
public int sets() {
return sizeMap.size();
}
}
public static int numIslands2(char[][] board) {
int row = board.length;
int col = board[0].length;
UnionFind uf = new UnionFind(board);
UnionFind2 uf = new UnionFind2(board);
for (int j = 1; j < col; j++) {
if (board[0][j - 1] == 1 && board[0][j] == 1) {
if (board[0][j - 1] == '1' && board[0][j] == '1') {
uf.union(0, j - 1, 0, j);
}
}
for (int i = 1; i < row; i++) {
if (board[i - 1][0] == 1 && board[i][0] == 1) {
if (board[i - 1][0] == '1' && board[i][0] == '1') {
uf.union(i - 1, 0, i, 0);
}
}
for (int i = 1; i < row; i++) {
for (int j = 1; j < col; j++) {
if (board[i][j] == 1) {
if (board[i][j - 1] == 1) {
if (board[i][j] == '1') {
if (board[i][j - 1] == '1') {
uf.union(i, j - 1, i, j);
}
if (board[i - 1][j] == 1) {
if (board[i - 1][j] == '1') {
uf.union(i - 1, j, i, j);
}
}
@ -103,14 +162,14 @@ public class Code06_IslandProblem {
return uf.sets();
}
public static class UnionFind {
public static class UnionFind2 {
private int[] parent;
private int[] size;
private int[] help;
private int col;
private int sets;
public UnionFind(int[][] board) {
public UnionFind2(char[][] board) {
col = board[0].length;
sets = 0;
int row = board.length;
@ -120,7 +179,7 @@ public class Code06_IslandProblem {
help = new int[len];
for (int r = 0; r < row; r++) {
for (int c = 0; c < col; c++) {
if (board[r][c] == 1) {
if (board[r][c] == '1') {
int i = index(r, c);
parent[i] = i;
size[i] = 1;
@ -169,20 +228,22 @@ public class Code06_IslandProblem {
}
public static int[][] generateRandomMatrix(int row, int col) {
int[][] board = new int[row][col];
// 为了测试
public static char[][] generateRandomMatrix(int row, int col) {
char[][] board = new char[row][col];
for (int i = 0; i < row; i++) {
for (int j = 0; j < col; j++) {
board[i][j] = Math.random() < 0.5 ? 1 : 0;
board[i][j] = Math.random() < 0.5 ? '1' : '0';
}
}
return board;
}
public static int[][] copy(int[][] board) {
// 为了测试
public static char[][] copy(char[][] board) {
int row = board.length;
int col = board[0].length;
int[][] ans = new int[row][col];
char[][] ans = new char[row][col];
for (int i = 0; i < row; i++) {
for (int j = 0; j < col; j++) {
ans[i][j] = board[i][j];
@ -191,12 +252,13 @@ public class Code06_IslandProblem {
return ans;
}
// 为了测试
public static void main(String[] args) {
int row = 0;
int col = 0;
int[][] board1 = null;
int[][] board2 = null;
int[][] board3 = null;
char[][] board1 = null;
char[][] board2 = null;
char[][] board3 = null;
long start = 0;
long end = 0;
@ -210,17 +272,17 @@ public class Code06_IslandProblem {
System.out.println("随机生成的二维矩阵规模 : " + row + " * " + col);
start = System.currentTimeMillis();
System.out.println("感染方法的运行结果: " + solve1(board1));
System.out.println("感染方法的运行结果: " + numIslands3(board1));
end = System.currentTimeMillis();
System.out.println("感染方法的运行时间: " + (end - start) + " ms");
start = System.currentTimeMillis();
System.out.println("并查集(map实现)的运行结果: " + solve2(board2));
System.out.println("并查集(map实现)的运行结果: " + numIslands1(board2));
end = System.currentTimeMillis();
System.out.println("并查集(map实现)的运行时间: " + (end - start) + " ms");
start = System.currentTimeMillis();
System.out.println("并查集(数组实现)的运行结果: " + solve3(board3));
System.out.println("并查集(数组实现)的运行结果: " + numIslands2(board3));
end = System.currentTimeMillis();
System.out.println("并查集(数组实现)的运行时间: " + (end - start) + " ms");
@ -234,12 +296,12 @@ public class Code06_IslandProblem {
System.out.println("随机生成的二维矩阵规模 : " + row + " * " + col);
start = System.currentTimeMillis();
System.out.println("感染方法的运行结果: " + solve1(board1));
System.out.println("感染方法的运行结果: " + numIslands3(board1));
end = System.currentTimeMillis();
System.out.println("感染方法的运行时间: " + (end - start) + " ms");
start = System.currentTimeMillis();
System.out.println("并查集(数组实现)的运行结果: " + solve3(board3));
System.out.println("并查集(数组实现)的运行结果: " + numIslands2(board3));
end = System.currentTimeMillis();
System.out.println("并查集(数组实现)的运行时间: " + (end - start) + " ms");

94
src/class09_15/Code03_NumberOfIslandsII.java
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@ -0,0 +1,94 @@
package class09_15;
import java.util.ArrayList;
import java.util.List;
public class Code03_NumberOfIslandsII {
public static List<Integer> numIslands2(int m, int n, int[][] positions) {
UnionFind unionFind = new UnionFind(m, n);
List<Integer> ans = new ArrayList<>();
for (int[] position : positions) {
unionFind.connect(position[0], position[1]);
ans.add(unionFind.sets());
}
return ans;
}
public static class UnionFind {
private int[] parent;
private int[] size;
private int[] help;
private final int col;
private final int row;
private int sets;
public UnionFind(int m, int n) {
row = m;
col = n;
sets = 0;
int len = row * col;
parent = new int[len];
size = new int[len];
help = new int[len];
}
private int index(int r, int c) {
return r * col + c;
}
private int find(int i) {
int hi = 0;
while (i != parent[i]) {
help[hi++] = i;
i = parent[i];
}
for (hi--; hi >= 0; hi--) {
parent[help[hi]] = i;
}
return i;
}
private void union(int r1, int c1, int r2, int c2) {
if (r1 < 0 || r1 == row || r2 < 0 || r2 == row || c1 < 0 || c1 == col || c2 < 0 || c2 == col) {
return;
}
int i1 = index(r1, c1);
int i2 = index(r2, c2);
if (size[i1] == 0 || size[i2] == 0) {
return;
}
int f1 = find(i1);
int f2 = find(i2);
if (f1 != f2) {
if (size[f1] >= size[f2]) {
size[f1] += size[f2];
parent[f2] = f1;
} else {
size[f2] += size[f1];
parent[f1] = f2;
}
sets--;
}
}
public void connect(int i, int j) {
int index = index(i, j);
if (size[index] == 0) {
parent[index] = index;
size[index] = 1;
sets++;
union(i - 1, j, i, j);
union(i + 1, j, i, j);
union(i, j - 1, i, j);
union(i, j + 1, i, j);
}
}
public int sets() {
return sets;
}
}
}
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