Added tasks 3678-3686

Author: javadev

src/main/java/g3601_3700/s3678_smallest_absent_positive_greater_than_average/Solution.java

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+package g3601_3700.s3678_smallest_absent_positive_greater_than_average;
+
+// #Easy #Biweekly_Contest_165 #2025_09_14_Time_10_ms_(100.00%)_Space_45.27_MB_(100.00%)
+
+import java.util.Arrays;
+import java.util.HashSet;
+import java.util.Set;
+
+public class Solution {
+    public int smallestAbsent(int[] nums) {
+        double avg;
+        double sum = 0;
+        Set<Integer> set = new HashSet<>();
+        for (int num : nums) {
+            sum += num;
+            set.add(num);
+        }
+        int n = nums.length;
+        Arrays.sort(nums);
+        avg = sum / n;
+        double j = avg < 0 ? 1 : Math.ceil(avg) == avg ? avg + 1 : Math.ceil(avg);
+        for (int i = (int) j; i <= 100; i++) {
+            if (!set.contains(i)) {
+                return i;
+            }
+        }
+        return nums[n - 1] + 1;
+    }
+}

src/main/java/g3601_3700/s3678_smallest_absent_positive_greater_than_average/readme.md

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+3678\. Smallest Absent Positive Greater Than Average
+
+Easy
+
+You are given an integer array `nums`.
+
+Return the **smallest absent positive** integer in `nums` such that it is **strictly greater** than the **average** of all elements in `nums`.
+
+The **average** of an array is defined as the sum of all its elements divided by the number of elements.
+
+**Example 1:**
+
+**Input:** nums = [3,5]
+
+**Output:** 6
+
+**Explanation:**
+
+*   The average of `nums` is `(3 + 5) / 2 = 8 / 2 = 4`.
+*   The smallest absent positive integer greater than 4 is 6.
+
+**Example 2:**
+
+**Input:** nums = [-1,1,2]
+
+**Output:** 3
+
+**Explanation:**
+
+*   The average of `nums` is `(-1 + 1 + 2) / 3 = 2 / 3 = 0.667`.
+*   The smallest absent positive integer greater than 0.667 is 3.
+
+**Example 3:**
+
+**Input:** nums = [4,-1]
+
+**Output:** 2
+
+**Explanation:**
+
+*   The average of `nums` is `(4 + (-1)) / 2 = 3 / 2 = 1.50`.
+*   The smallest absent positive integer greater than 1.50 is 2.
+
+**Constraints:**
+
+*   `1 <= nums.length <= 100`
+*   `-100 <= nums[i] <= 100`

src/main/java/g3601_3700/s3679_minimum_discards_to_balance_inventory/Solution.java

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+package g3601_3700.s3679_minimum_discards_to_balance_inventory;
+
+// #Medium #Biweekly_Contest_165 #2025_09_14_Time_30_ms_(100.00%)_Space_61.57_MB_(100.00%)
+
+import java.util.HashMap;
+import java.util.Map;
+
+public class Solution {
+    public int minArrivalsToDiscard(int[] arrivals, int w, int m) {
+        int n = arrivals.length;
+        if (n == 0) {
+            return 0;
+        }
+        Map<Integer, Integer> map = new HashMap<>();
+        int[] kept = new int[n];
+        int dis = 0;
+        for (int i = 0; i < n; i++) {
+            int idx = i - w;
+            if (idx >= 0 && kept[idx] == 1) {
+                map.put(arrivals[idx], map.get(arrivals[idx]) - 1);
+            }
+            int t = arrivals[i];
+            if (map.getOrDefault(t, 0) < m) {
+                kept[i] = 1;
+                map.put(t, map.getOrDefault(t, 0) + 1);
+            } else {
+                dis++;
+            }
+        }
+        return dis;
+    }
+}

src/main/java/g3601_3700/s3679_minimum_discards_to_balance_inventory/readme.md

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+3679\. Minimum Discards to Balance Inventory
+
+Medium
+
+You are given two integers `w` and `m`, and an integer array `arrivals`, where `arrivals[i]` is the type of item arriving on day `i` (days are **1-indexed**).
+
+Items are managed according to the following rules:
+
+*   Each arrival may be **kept** or **discarded**; an item may only be discarded on its arrival day.
+*   For each day `i`, consider the window of days `[max(1, i - w + 1), i]` (the `w` most recent days up to day `i`):
+    *   For **any** such window, each item type may appear **at most** `m` times among kept arrivals whose arrival day lies in that window.
+    *   If keeping the arrival on day `i` would cause its type to appear **more than** `m` times in the window, that arrival **must** be discarded.
+
+Return the **minimum** number of arrivals to be discarded so that every `w`\-day window contains at most `m` occurrences of each type.
+
+**Example 1:**
+
+**Input:** arrivals = [1,2,1,3,1], w = 4, m = 2
+
+**Output:** 0
+
+**Explanation:**
+
+*   On day 1, Item 1 arrives; the window contains no more than `m` occurrences of this type, so we keep it.
+*   On day 2, Item 2 arrives; the window of days 1 - 2 is fine.
+*   On day 3, Item 1 arrives, window `[1, 2, 1]` has item 1 twice, within limit.
+*   On day 4, Item 3 arrives, window `[1, 2, 1, 3]` has item 1 twice, allowed.
+*   On day 5, Item 1 arrives, window `[2, 1, 3, 1]` has item 1 twice, still valid.
+
+There are no discarded items, so return 0.
+
+**Example 2:**
+
+**Input:** arrivals = [1,2,3,3,3,4], w = 3, m = 2
+
+**Output:** 1
+
+**Explanation:**
+
+*   On day 1, Item 1 arrives. We keep it.
+*   On day 2, Item 2 arrives, window `[1, 2]` is fine.
+*   On day 3, Item 3 arrives, window `[1, 2, 3]` has item 3 once.
+*   On day 4, Item 3 arrives, window `[2, 3, 3]` has item 3 twice, allowed.
+*   On day 5, Item 3 arrives, window `[3, 3, 3]` has item 3 three times, exceeds limit, so the arrival must be discarded.
+*   On day 6, Item 4 arrives, window `[3, 4]` is fine.
+
+Item 3 on day 5 is discarded, and this is the minimum number of arrivals to discard, so return 1.
+
+**Constraints:**
+
+*   <code>1 <= arrivals.length <= 10<sup>5</sup></code>
+*   <code>1 <= arrivals[i] <= 10<sup>5</sup></code>
+*   `1 <= w <= arrivals.length`
+*   `1 <= m <= w`

src/main/java/g3601_3700/s3680_generate_schedule/Solution.java

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+package g3601_3700.s3680_generate_schedule;
+
+// #Medium #Biweekly_Contest_165 #2025_09_14_Time_67_ms_(100.00%)_Space_45.58_MB_(100.00%)
+
+import java.util.Arrays;
+import java.util.Comparator;
+
+public class Solution {
+    public int[][] generateSchedule(int n) {
+        int[][] res = new int[n * (n - 1)][2];
+        boolean[][] matches = new boolean[n][n];
+        res[0] = new int[] {0, 1};
+        matches[0][1] = true;
+        int[] matchesCount = new int[n];
+        matchesCount[0] = 1;
+        matchesCount[1] = 1;
+        if (backtrack(n, matches, res, 1, matchesCount)) {
+            return res;
+        }
+        return new int[][] {};
+    }
+
+    private boolean backtrack(
+            int n, boolean[][] matches, int[][] result, int cur, int[] matchesCount) {
+        if (cur == result.length) {
+            return true;
+        }
+        Integer[] teams = new Integer[n];
+        for (int i = 0; i < n; i++) {
+            teams[i] = i;
+        }
+        Arrays.sort(teams, Comparator.comparingInt(a -> matchesCount[a]));
+        for (int i = 0; i < n; i++) {
+            if (result[cur - 1][0] != teams[i] && result[cur - 1][1] != teams[i]) {
+                int team1 = -1;
+                int team2 = -1;
+                for (int j = 0; j < n; j++) {
+                    if (i != j
+                            && !matches[teams[i]][teams[j]]
+                            && result[cur - 1][0] != teams[j]
+                            && result[cur - 1][1] != teams[j]) {
+                        team1 = teams[i];
+                        team2 = teams[j];
+                        break;
+                    }
+                }
+                if (team1 != -1) {
+                    result[cur] = new int[] {team1, team2};
+                    matches[team1][team2] = true;
+                    matchesCount[team1]++;
+                    matchesCount[team2]++;
+                    boolean found = backtrack(n, matches, result, cur + 1, matchesCount);
+                    if (found) {
+                        return true;
+                    } else {
+                        matches[team1][team2] = false;
+                        result[cur] = new int[] {0, 0};
+                        matchesCount[team1]--;
+                        matchesCount[team2]--;
+                    }
+                }
+            }
+        }
+        return false;
+    }
+}

src/main/java/g3601_3700/s3680_generate_schedule/readme.md

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+3680\. Generate Schedule
+
+Medium
+
+You are given an integer `n` representing `n` teams. You are asked to generate a schedule such that:
+
+*   Each team plays every other team **exactly twice**: once at home and once away.
+*   There is **exactly one** match per day; the schedule is a list of **consecutive** days and `schedule[i]` is the match on day `i`.
+*   No team plays on **consecutive** days.
+
+Return a 2D integer array `schedule`, where `schedule[i][0]` represents the home team and `schedule[i][1]` represents the away team. If multiple schedules meet the conditions, return **any** one of them.
+
+If no schedule exists that meets the conditions, return an empty array.
+
+**Example 1:**
+
+**Input:** n = 3
+
+**Output:** []
+
+**Explanation:**
+
+Since each team plays every other team exactly twice, a total of 6 matches need to be played: `[0,1],[0,2],[1,2],[1,0],[2,0],[2,1]`.
+
+It's not possible to create a schedule without at least one team playing consecutive days.
+
+**Example 2:**
+
+**Input:** n = 5
+
+**Output:** [[0,1],[2,3],[0,4],[1,2],[3,4],[0,2],[1,3],[2,4],[0,3],[1,4],[2,0],[3,1],[4,0],[2,1],[4,3],[1,0],[3,2],[4,1],[3,0],[4,2]]
+
+**Explanation:**
+
+Since each team plays every other team exactly twice, a total of 20 matches need to be played.
+
+The output shows one of the schedules that meet the conditions. No team plays on consecutive days.
+
+**Constraints:**
+
+*   `2 <= n <= 50`

src/main/java/g3601_3700/s3681_maximum_xor_of_subsequences/Solution.java

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+package g3601_3700.s3681_maximum_xor_of_subsequences;
+
+// #Hard #Biweekly_Contest_165 #2025_09_14_Time_29_ms_(100.00%)_Space_58.02_MB_(100.00%)
+
+public class Solution {
+    public int maxXorSubsequences(int[] nums) {
+        int n = nums.length;
+        if (n == 0) {
+            return 0;
+        }
+        int x = 0;
+        while (true) {
+            int y = 0;
+            for (int v : nums) {
+                if (v > y) {
+                    y = v;
+                }
+            }
+            if (y == 0) {
+                return x;
+            }
+            x = Math.max(x, x ^ y);
+            for (int i = 0; i < n; i++) {
+                int v = nums[i];
+                nums[i] = Math.min(v, v ^ y);
+            }
+        }
+    }
+}

src/main/java/g3601_3700/s3681_maximum_xor_of_subsequences/readme.md

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+3681\. Maximum XOR of Subsequences
+
+Hard
+
+You are given an integer array `nums` of length `n` where each element is a non-negative integer.
+
+Select **two** **subsequences** of `nums` (they may be empty and are **allowed** to **overlap**), each preserving the original order of elements, and let:
+
+*   `X` be the bitwise XOR of all elements in the first subsequence.
+*   `Y` be the bitwise XOR of all elements in the second subsequence.
+
+Return the **maximum** possible value of `X XOR Y`.
+
+**Note:** The XOR of an **empty** subsequence is 0.
+
+**Example 1:**
+
+**Input:** nums = [1,2,3]
+
+**Output:** 3
+
+**Explanation:**
+
+Choose subsequences:
+
+*   First subsequence `[2]`, whose XOR is 2.
+*   Second subsequence `[2,3]`, whose XOR is 1.
+
+Then, XOR of both subsequences = `2 XOR 1 = 3`.
+
+This is the maximum XOR value achievable from any two subsequences.
+
+**Example 2:**
+
+**Input:** nums = [5,2]
+
+**Output:** 7
+
+**Explanation:**
+
+Choose subsequences:
+
+*   First subsequence `[5]`, whose XOR is 5.
+*   Second subsequence `[2]`, whose XOR is 2.
+
+Then, XOR of both subsequences = `5 XOR 2 = 7`.
+
+This is the maximum XOR value achievable from any two subsequences.
+
+**Constraints:**
+
+*   <code>2 <= nums.length <= 10<sup>5</sup></code>
+*   <code>0 <= nums[i] <= 10<sup>9</sup></code>

src/main/java/g3601_3700/s3683_earliest_time_to_finish_one_task/Solution.java

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+package g3601_3700.s3683_earliest_time_to_finish_one_task;
+
+// #Easy #Weekly_Contest_467 #2025_09_14_Time_1_ms_(100.00%)_Space_44.90_MB_(100.00%)
+
+public class Solution {
+    public int earliestTime(int[][] tasks) {
+        if (tasks.length == 1) {
+            int sum = 0;
+            for (int t : tasks[0]) {
+                sum += t;
+            }
+            return sum;
+        }
+        int minTask = 0;
+        for (int t : tasks[0]) {
+            minTask += t;
+        }
+        for (int i = 1; i < tasks.length; i++) {
+            int sum = 0;
+            for (int t : tasks[i]) {
+                sum += t;
+            }
+            if (sum < minTask) {
+                minTask = sum;
+            }
+        }
+        return minTask;
+    }
+}