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Commit f6f2049

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LeetCode 题解 1574~1584
1 parent 782092c commit f6f2049

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7 files changed

+236
-0
lines changed

7 files changed

+236
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lines changed
Lines changed: 30 additions & 0 deletions
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class Solution {
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public int findLengthOfShortestSubarray(int[] arr) {
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int n = arr.length;
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int left = 0;
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while (left + 1 < n && arr[left] <= arr[left + 1]) {
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left++;
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}
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if (left == n - 1) {
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return 0;
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}
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int right = n - 1;
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while (right > 0 && arr[right - 1] <= arr[right]) {
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right--;
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}
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int res = Math.min(n - left - 1, right);
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int i = 0, j = right;
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while (i <= left && j <= n - 1) {
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if (arr[i] <= arr[j]) {
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res = Math.min(res, j - i - 1);
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i++;
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} else {
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j++;
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}
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}
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return res;
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}
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}
Lines changed: 20 additions & 0 deletions
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class Solution {
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public String modifyString(String s) {
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char[] chars = s.toCharArray();
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for (int i = 0; i < chars.length; i++) {
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if (chars[i] == '?') {
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// 前面的字符
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char ahead = i == 0 ? ' ' : chars[i - 1];
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// 最后的字符
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char behind = i == chars.length - 1 ? ' ' : chars[i + 1];
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char temp = 'a';
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while (temp == ahead || temp == behind ) {
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temp++;
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}
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chars[i] = temp;
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}
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}
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return new String(chars);
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}
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}
Lines changed: 19 additions & 0 deletions
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class Solution {
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public int minCost(String s, int[] cost) {
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int res = 0;
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char[] word = s.toCharArray();
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for(int i = 0;i < word.length;i++){
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char c = word[i];
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int max = cost[i];
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int sum = max;
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while(i + 1 < word.length && word[i + 1] == c){
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sum += cost[++i];
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max = Math.max(max,cost[i]);
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}
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if(sum != max){
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res += sum - max;
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}
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}
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return res;
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}
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}
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class Solution {
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// https://oi-wiki.org/ds/dsu/#_3
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private boolean[] used;
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public int maxNumEdgesToRemove(int n, int[][] edges) {
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used = new boolean[edges.length];
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// type 为倒序,3, 2, 1
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Arrays.sort(edges, (a, b) -> Integer.compare(b[0], a[0]));
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if (!unionFind(n, edges, 1)) return -1;
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if (!unionFind(n, edges, 2)) return -1;
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int result = 0;
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for (boolean u : used) {
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result += u ? 0 : 1;
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}
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return result;
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}
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private boolean unionFind(int n, int[][] edges, int excludedType) {
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int[] union = new int[n + 1];
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for (int i = 1; i <= n; i++) {
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union[i] = i;
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}
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int cnt = 0;
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for (int i = 0; i < edges.length; i++) {
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int[] edge = edges[i];
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if (edge[0] == excludedType) continue;
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int rootA = findRoot(union, edge[1]);
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int rootB = findRoot(union, edge[2]);
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if (rootA != rootB) {
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cnt += 1;
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union[rootA] = rootB;
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used[i] = true;
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}
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if (cnt == n - 1) return true;
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}
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return false;
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}
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private int findRoot(int[] union, int idx) {
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if (union[idx] != idx) {
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int root = findRoot(union, union[idx]);
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union[idx] = root;
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return root;
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}
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return idx;
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}
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}
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class Solution {
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public int numSpecial(int[][] mat) {
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int rows = mat.length;
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int cols = mat[0].length;
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int[] rows1 = new int[rows];
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int[] cols1 = new int[cols];
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for (int i = 0; i < rows; i++) {
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for (int j = 0; j < cols; j++) {
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if (mat[i][j] == 1) {
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rows1[i]++;
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cols1[j]++;
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}
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}
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}
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int ans = 0;
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for (int i = 0; i < rows; i++) {
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for (int j = 0; j < cols; j++) {
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if (mat[i][j] == 1 && rows1[i] == 1 && cols1[j] == 1) {
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ans ++;
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}
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}
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}
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return ans;
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}
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}
Lines changed: 46 additions & 0 deletions
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class Solution {
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public int unhappyFriends(int n, int[][] preferences, int[][] pairs) {
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Map<Integer, Set<Integer>> map = new HashMap<>();
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for (int[] pair : pairs) {
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calcBetter(preferences[pair[0]], map, pair[0], pair[1]);
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calcBetter(preferences[pair[1]], map, pair[1], pair[0]);
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}
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Set<Integer> set = new HashSet<>();
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for (int i = 0; i < pairs.length; i++) {
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for (int j = i + 1; j < pairs.length; j++) {
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if (unhappy(pairs[i][0], pairs[j][0], map)) {
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set.add(pairs[i][0]);
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set.add(pairs[j][0]);
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}
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if (unhappy(pairs[i][1], pairs[j][0], map)) {
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set.add(pairs[i][1]);
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set.add(pairs[j][0]);
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}
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if (unhappy(pairs[i][0], pairs[j][1], map)) {
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set.add(pairs[i][0]);
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set.add(pairs[j][1]);
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}
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if (unhappy(pairs[i][1], pairs[j][1], map)) {
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set.add(pairs[i][1]);
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set.add(pairs[j][1]);
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}
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}
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}
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return set.size();
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}
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private void calcBetter(int[] preference, Map<Integer, Set<Integer>> map, int from, int to) {
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Set<Integer> betterSet = new HashSet<>();
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for (int i : preference) {
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if (i == to) {
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break;
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}
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betterSet.add(i);
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}
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map.put(from, betterSet);
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}
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private boolean unhappy(int x, int y, Map<Integer, Set<Integer>> map) {
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return map.get(x).contains(y) && map.get(y).contains(x);
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}
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}
Lines changed: 46 additions & 0 deletions
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class Solution {
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static class Edge {
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int x;
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int y;
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int len;
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Edge(int x, int y, int len) {
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this.x = x;
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this.y = y;
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this.len = len;
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}
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}
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public int minCostConnectPoints(int[][] points) {
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Queue<Edge> heap = new PriorityQueue<>(Comparator.comparingInt((Edge e) -> e.len));
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boolean[] marked = new boolean[points.length];
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marked[0] = true;
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addVertex(points, marked, 0, heap);
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int count = 1;
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int res = 0;
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while (!heap.isEmpty()) {
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Edge edge = heap.poll();
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if (!marked[edge.y]) {
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res += edge.len;
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marked[edge.y] = true;
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addVertex(points, marked, edge.y, heap);
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count++;
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if (count == points.length) {
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break;
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}
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}
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}
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return res;
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}
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public void addVertex(int[][] points, boolean[] marked, int x, Queue<Edge> heap) {
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for (int i = 0; i < marked.length; i++) {
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if (marked[i]) {
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continue;
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}
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heap.add(new Edge(x, i,
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Math.abs(points[x][0] - points[i][0]) + Math.abs(points[x][1] - points[i][1])));
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}
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}
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}

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