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weekly contest 338
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‎README.md

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@@ -5,6 +5,8 @@ Record leetcode contest and ideas every week, and encourage yourself to think mo
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leetcode url: <https://leetcode.cn/u/cctest/>
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* ☀️ [weekly contest 338](src/main/java/weekly/wk338.java) 贪心 | 谈心 | 前缀和+二分 | 拓扑排序
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* ☀️ [weekly contest 337](src/main/java/weekly/wk337.java) 模拟 | 模拟 | 回溯 | 同余分组
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* 🐎️ [weekly contest 336](src/main/java/weekly/wk336.java) 模拟 | 排序 | 异或前缀和 | 贪心
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* 🐎️ [weekly contest 335](src/main/java/weekly/wk335.java) 模拟 | 层序遍历 | 质数分解 | 多重背包

‎src/main/java/weekly/wk338.java

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package weekly;
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import java.util.ArrayList;
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import java.util.Arrays;
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import java.util.HashMap;
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import java.util.HashSet;
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import java.util.LinkedList;
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import java.util.List;
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import java.util.Map;
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import java.util.Queue;
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import java.util.Set;
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import java.util.TreeMap;
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import java.util.TreeSet;
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public class wk338 {
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//贪心
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public int kItemsWithMaximumSum(int numOnes, int numZeros, int numNegOnes, int k) {
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if (numOnes >= k) {
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return k;
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} else if (numOnes + numZeros >= k) {
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return numOnes;
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} else {
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return numOnes - (k - numOnes - numZeros);
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}
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}
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//贪心 减去能减的最大质数
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public boolean primeSubOperation(int[] nums) {
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int n = 1000;
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TreeSet<Integer> treeSet = new TreeSet<>();
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boolean[] Prime = new boolean[n];
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Prime[0] = true;
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for (int i = 2; i <= n; i++) {
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boolean isPrime = true;
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for (int j = 2; j <= i / 2; j++) {
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if (i % j == 0) {
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isPrime = false;
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break;
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}
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}
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if (isPrime) {
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Prime[i] = true;
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treeSet.add(i);
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}
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}
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for (int i = nums[0] - 1; i >= 0; i--) {
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if (Prime[i]) {
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nums[0] -= i;
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break;
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}
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}
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for (int i = 1; i < nums.length; i++) {
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boolean flag = false;
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for (int j = nums[i] - 1; j >= 0; j--) {
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if (Prime[j] && nums[i] - j > nums[i - 1]) {
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nums[i] -= j;
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flag = true;
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break;
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}
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}
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if (!flag) {
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return false;
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}
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}
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return true;
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}
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//前缀和+二分
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public List<Long> minOperations(int[] nums, int[] queries) {
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int[][] q = new int[queries.length][2];
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for (int i = 0; i < queries.length; i++) {
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q[i] = new int[]{queries[i], i};
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}
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Arrays.sort(q, (a, b) -> a[0] - b[0]);
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Arrays.sort(nums);
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long[] res = new long[queries.length];
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int left = 0;
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long sum = 0;
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for (int i = 0; i < nums.length; i++) {
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if (nums[i] <= q[0][0]) {
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left++;
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sum += q[0][0] - nums[i];
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} else {
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sum += nums[i] - q[0][0];
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}
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}
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res[q[0][1]] = sum;
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for (int i = 1; i < q.length; i++) {
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int dis = q[i][0] - q[i - 1][0];
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int count = 0;
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while (left + count < nums.length && nums[left + count] < q[i][0]) {
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sum += (q[i][0] - nums[left + count]) - (nums[left + count] - q[i - 1][0]);
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count++;
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}
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sum += ((long) left - (nums.length - left - count)) * dis;
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res[q[i][1]] = sum;
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left += count;
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}
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List<Long> ans = new ArrayList<>();
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for (long re : res) {
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ans.add(re);
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}
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return ans;
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}
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//两次拓扑排序:一次从0一直找，一次从1找两次
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public int collectTheCoins(int[] coins, int[][] edges) {
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// 构建无向图
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int n = coins.length;
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int[] in = new int[coins.length];
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Map<Integer, List<Integer>> graph = new HashMap<>();
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for (int i = 0; i < n; i++) {
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graph.put(i, new ArrayList<>());
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}
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for (int[] edge : edges) {
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int u = edge[0], v = edge[1];
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graph.get(u).add(v);
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graph.get(v).add(u);
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in[u]++;
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in[v]++;
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}
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Queue<Integer> queue = new LinkedList<>();
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for (int i = 0; i < in.length; i++) {
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if (in[i] == 1) {
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queue.add(i);
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}
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}
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Set<Integer> remove = new HashSet<>();
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help(remove, graph, in, coins);
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help2(remove, graph, in, coins);
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return 2 * (Math.max(0, coins.length - remove.size() - 1));
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}
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//0遍历到底
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void help(Set<Integer> remove, Map<Integer, List<Integer>> graph, int[] in, int[] coins) {
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Queue<Integer> queue = new LinkedList<>();
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for (int i = 0; i < in.length; i++) {
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if (in[i] == 1 && coins[i] == 0) {
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queue.add(i);
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}
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}
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while (!queue.isEmpty()) {
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Integer cur = queue.poll();
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remove.add(cur);
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in[cur] = 0;
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for (Integer next : graph.getOrDefault(cur, new ArrayList<>())) {
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in[next]--;
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if (coins[next] == 0 && in[next] == 1) {
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queue.add(next);
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}
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}
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}
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}
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void help2(Set<Integer> remove, Map<Integer, List<Integer>> graph, int[] in, int[] coins) {
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Queue<Integer> queue = new LinkedList<>();
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for (int i = 0; i < in.length; i++) {
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if (in[i] == 1 && coins[i] == 1) {
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queue.add(i);
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}
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}
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int step = 0;
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while (!queue.isEmpty()) {
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int size = queue.size();
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while (size-- > 0) {
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Integer cur = queue.poll();
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remove.add(cur);
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in[cur] = 0;
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for (Integer next : graph.getOrDefault(cur, new ArrayList<>())) {
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in[next]--;
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if (in[next] == 1) {
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queue.add(next);
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}
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}
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}
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step++;
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if (step >= 2) return;
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}
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}
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public static void main(String[] args) {
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wk338 w = new wk338();
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w.collectTheCoins(new int[]{1, 0, 0, 1, 1, 0, 0, 0, 0, 1, 0, 0},
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new int[][]{{0, 1}, {1, 2}, {1, 3}, {2, 4}, {4, 5}, {5, 6}, {5, 7}, {4, 8}, {7, 9}, {7, 10}, {10, 11}});
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}
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}

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