Added tasks 3760-3770

Author: ThanhNIT

src/main/java/g3701_3800/s3760_maximum_substrings_with_distinct_start/Solution.java

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+package g3701_3800.s3760_maximum_substrings_with_distinct_start;
+
+// #Medium #String #Hash_Table #Senior #Weekly_Contest_478
+// #2026_05_08_Time_5_ms_(98.92%)_Space_47.79_MB_(74.99%)
+
+public class Solution {
+    public int maxDistinct(String s) {
+        int mask = 0;
+        int res = 0;
+        for (char c : s.toCharArray()) {
+            int bit = 1 << (c - 'a');
+            if ((mask & bit) == 0) {
+                mask |= bit;
+                res++;
+                if (res == 26) {
+                    break;
+                }
+            }
+        }
+        return res;
+    }
+}

src/main/java/g3701_3800/s3760_maximum_substrings_with_distinct_start/readme.md

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+3760\. Maximum Substrings With Distinct Start
+
+Medium
+
+You are given a string `s` consisting of lowercase English letters.
+
+Return an integer denoting the **maximum** number of substring you can split `s` into such that each **substring** starts with a **distinct** character (i.e., no two substrings start with the same character).
+
+**Example 1:**
+
+**Input:** s = "abab"
+
+**Output:** 2
+
+**Explanation:**
+
+*   Split `"abab"` into `"a"` and `"bab"`.
+*   Each substring starts with a distinct character i.e `'a'` and `'b'`. Thus, the answer is 2.
+
+**Example 2:**
+
+**Input:** s = "abcd"
+
+**Output:** 4
+
+**Explanation:**
+
+*   Split `"abcd"` into `"a"`, `"b"`, `"c"`, and `"d"`.
+*   Each substring starts with a distinct character. Thus, the answer is 4.
+
+**Example 3:**
+
+**Input:** s = "aaaa"
+
+**Output:** 1
+
+**Explanation:**
+
+*   All characters in `"aaaa"` are `'a'`.
+*   Only one substring can start with `'a'`. Thus, the answer is 1.
+
+**Constraints:**
+
+*   <code>1 <= s.length <= 10<sup>5</sup></code>
+*   `s` consists of lowercase English letters.

src/main/java/g3701_3800/s3761_minimum_absolute_distance_between_mirror_pairs/Solution.java

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+package g3701_3800.s3761_minimum_absolute_distance_between_mirror_pairs;
+
+// #Medium #Array #Hash_Table #Math #Staff #Weekly_Contest_478
+// #2026_05_08_Time_49_ms_(84.83%)_Space_95.13_MB_(49.31%)
+
+import java.util.HashMap;
+
+public class Solution {
+    public int minMirrorPairDistance(int[] nums) {
+        int res = 100000;
+        int i = 0;
+        HashMap<Integer, Integer> seen = new HashMap<>();
+        for (int n : nums) {
+            int r;
+            if (seen.containsKey(n)) {
+                res = Math.min(res, i - seen.get(n));
+            }
+            for (r = 0; n > 0; n /= 10) {
+                r = r * 10 + (n % 10);
+            }
+            seen.put(r, i++);
+        }
+
+        return res == 100000 ? -1 : res;
+    }
+}

src/main/java/g3701_3800/s3761_minimum_absolute_distance_between_mirror_pairs/readme.md

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+3761\. Minimum Absolute Distance Between Mirror Pairs
+
+Medium
+
+You are given an integer array `nums`.
+
+A **mirror pair** is a pair of indices `(i, j)` such that:
+
+*   `0 <= i < j < nums.length`, and
+*   `reverse(nums[i]) == nums[j]`, where `reverse(x)` denotes the integer formed by reversing the digits of `x`. Leading zeros are omitted after reversing, for example `reverse(120) = 21`.
+
+Return the **minimum** absolute distance between the indices of any mirror pair. The absolute distance between indices `i` and `j` is `abs(i - j)`.
+
+If no mirror pair exists, return `-1`.
+
+**Example 1:**
+
+**Input:** nums = [12,21,45,33,54]
+
+**Output:** 1
+
+**Explanation:**
+
+The mirror pairs are:
+
+*   (0, 1) since `reverse(nums[0]) = reverse(12) = 21 = nums[1]`, giving an absolute distance `abs(0 - 1) = 1`.
+*   (2, 4) since `reverse(nums[2]) = reverse(45) = 54 = nums[4]`, giving an absolute distance `abs(2 - 4) = 2`.
+
+The minimum absolute distance among all pairs is 1.
+
+**Example 2:**
+
+**Input:** nums = [120,21]
+
+**Output:** 1
+
+**Explanation:**
+
+There is only one mirror pair (0, 1) since `reverse(nums[0]) = reverse(120) = 21 = nums[1]`.
+
+The minimum absolute distance is 1.
+
+**Example 3:**
+
+**Input:** nums = [21,120]
+
+**Output:** \-1
+
+**Explanation:**
+
+There are no mirror pairs in the array.
+
+**Constraints:**
+
+*   <code>1 <= nums.length <= 10<sup>5</sup></code>
+*   <code>1 <= nums[i] <= 10<sup>9</sup></code>

src/main/java/g3701_3800/s3762_minimum_operations_to_equalize_subarrays/Solution.java

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+package g3701_3800.s3762_minimum_operations_to_equalize_subarrays;
+
+// #Hard #Array #Math #Binary_Search #Segment_Tree #Weekly_Contest_478 #Principal
+// #2026_05_08_Time_528_ms_(100.00%)_Space_267.97_MB_(76.92%)
+
+import java.util.ArrayList;
+import java.util.Comparator;
+import java.util.HashMap;
+import java.util.Map;
+
+public class Solution {
+    private static class MNode {
+        int l;
+        int r;
+        int[] vals;
+        long[] pref;
+        MNode left;
+        MNode right;
+
+        MNode(int l, int r) {
+            this.l = l;
+            this.r = r;
+        }
+    }
+
+    private static class Group {
+        int[] pos;
+        int[] val;
+        long[] prefPos;
+        MNode root;
+        int minv;
+        int maxv;
+    }
+
+    private static int lowerBound(int[] a, int x) {
+        int l = 0;
+        int r = a.length;
+        while (l < r) {
+            int m = (l + r) >>> 1;
+            if (a[m] >= x) {
+                r = m;
+            } else {
+                l = m + 1;
+            }
+        }
+        return l;
+    }
+
+    private int upperBound(int[] a, int x) {
+        int l = 0;
+        int r = a.length;
+        while (l < r) {
+            int m = (l + r) >>> 1;
+            if (a[m] > x) {
+                r = m;
+            } else {
+                l = m + 1;
+            }
+        }
+        return l;
+    }
+
+    private MNode buildMerge(int[] arr, int l, int r) {
+        MNode node = new MNode(l, r);
+        if (l == r) {
+            node.vals = new int[] {arr[l]};
+            node.pref = new long[] {arr[l]};
+            return node;
+        }
+        int m = (l + r) >>> 1;
+        node.left = buildMerge(arr, l, m);
+        node.right = buildMerge(arr, m + 1, r);
+        int[] a = node.left.vals;
+        int[] b = node.right.vals;
+        int na = a.length;
+        int nb = b.length;
+        int[] c = new int[na + nb];
+        long[] pref = new long[na + nb];
+        int ia = 0;
+        int ib = 0;
+        int k = 0;
+        while (ia < na && ib < nb) {
+            if (a[ia] <= b[ib]) {
+                c[k++] = a[ia++];
+            } else {
+                c[k++] = b[ib++];
+            }
+        }
+        while (ia < na) {
+            c[k++] = a[ia++];
+        }
+        while (ib < nb) {
+            c[k++] = b[ib++];
+        }
+        pref[0] = c[0];
+        for (int i = 1; i < c.length; i++) {
+            pref[i] = pref[i - 1] + c[i];
+        }
+        node.vals = c;
+        node.pref = pref;
+        return node;
+    }
+
+    private int countLE(MNode node, int ql, int qr, int x) {
+        if (node == null || ql > node.r || qr < node.l) {
+            return 0;
+        }
+        if (ql <= node.l && node.r <= qr) {
+            int idx = upperBound(node.vals, x) - 1;
+            return idx < 0 ? 0 : idx + 1;
+        }
+        return countLE(node.left, ql, qr, x) + countLE(node.right, ql, qr, x);
+    }
+
+    private long sumLE(MNode node, int ql, int qr, int x) {
+        if (node == null || ql > node.r || qr < node.l) {
+            return 0L;
+        }
+        if (ql <= node.l && node.r <= qr) {
+            int idx = upperBound(node.vals, x) - 1;
+            return idx < 0 ? 0L : node.pref[idx];
+        }
+        return sumLE(node.left, ql, qr, x) + sumLE(node.right, ql, qr, x);
+    }
+
+    public long[] minOperations(int[] nums, int k, int[][] queries) {
+        Map<Integer, Group> groupHashMap = buildGroups(nums, k);
+        long[] ans = new long[queries.length];
+        for (int qi = 0; qi < queries.length; qi++) {
+            ans[qi] = processQuery(nums, queries[qi], groupHashMap, k);
+        }
+        return ans;
+    }
+
+    private Map<Integer, Group> buildGroups(int[] nums, int k) {
+        Map<Integer, ArrayList<int[]>> map = new HashMap<>();
+        for (int i = 0; i < nums.length; i++) {
+            int rem = nums[i] % k;
+            int value = nums[i] / k;
+            map.computeIfAbsent(rem, z -> new ArrayList<>()).add(new int[] {i, value});
+        }
+        Map<Integer, Group> groupHashMap = new HashMap<>();
+        for (Map.Entry<Integer, ArrayList<int[]>> entry : map.entrySet()) {
+            groupHashMap.put(entry.getKey(), createGroup(entry.getValue()));
+        }
+        return groupHashMap;
+    }
+
+    private Group createGroup(ArrayList<int[]> arr) {
+        arr.sort(Comparator.comparingInt(a -> a[0]));
+        int size = arr.size();
+        int[] pos = new int[size];
+        int[] val = new int[size];
+        long[] prefPos = new long[size];
+        int min = Integer.MAX_VALUE;
+        int max = Integer.MIN_VALUE;
+        for (int i = 0; i < size; i++) {
+            pos[i] = arr.get(i)[0];
+            val[i] = arr.get(i)[1];
+            min = Math.min(min, val[i]);
+            max = Math.max(max, val[i]);
+            prefPos[i] = i == 0 ? val[i] : prefPos[i - 1] + val[i];
+        }
+        Group group = new Group();
+        group.pos = pos;
+        group.val = val;
+        group.prefPos = prefPos;
+        group.minv = min;
+        group.maxv = max;
+        if (size > 0) {
+            group.root = buildMerge(val, 0, size - 1);
+        }
+        return group;
+    }
+
+    private long processQuery(int[] nums, int[] query, Map<Integer, Group> groupHashMap, int k) {
+        int left = query[0];
+        int right = query[1];
+        int rem = nums[left] % k;
+        Group group = groupHashMap.get(rem);
+        if (group == null) {
+            return -1;
+        }
+        int l = lowerBound(group.pos, left);
+        int r = upperBound(group.pos, right) - 1;
+        if (!isValidRange(left, right, l, r)) {
+            return -1;
+        }
+        return calculateOperations(group, l, r);
+    }
+
+    private boolean isValidRange(int left, int right, int l, int r) {
+        return l <= r && (r - l + 1 == right - left + 1);
+    }
+
+    private long calculateOperations(Group group, int l, int r) {
+        int count = r - l + 1;
+        int median = findMedian(group, l, r, count);
+        long leftCount = countLE(group.root, l, r, median);
+        long leftSum = sumLE(group.root, l, r, median);
+        long total = group.prefPos[r] - (l == 0 ? 0L : group.prefPos[l - 1]);
+        long rightSum = total - leftSum;
+        long rightCount = count - leftCount;
+        return median * leftCount - leftSum + rightSum - median * rightCount;
+    }
+
+    private int findMedian(Group group, int l, int r, int count) {
+        int need = (count + 1) / 2;
+        int low = group.minv;
+        int high = group.maxv;
+        while (low < high) {
+            int mid = low + ((high - low) >>> 1);
+            int currentCount = countLE(group.root, l, r, mid);
+            if (currentCount >= need) {
+                high = mid;
+            } else {
+                low = mid + 1;
+            }
+        }
+        return low;
+    }
+}