Added tasks 3556-3663

src/main/java/g3501_3600/s3556_sum_of_largest_prime_substrings/Solution.java

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+package g3501_3600.s3556_sum_of_largest_prime_substrings;
+
+// #Medium #String #Hash_Table #Math #Sorting #Number_Theory
+// #2025_05_27_Time_7_ms_(99.93%)_Space_42.77_MB_(98.34%)
+
+import java.util.HashSet;
+import java.util.Set;
+
+public class Solution {
+    public long sumOfLargestPrimes(String s) {
+        Set<Long> set = new HashSet<>();
+        int n = s.length();
+        long first = -1;
+        long second = -1;
+        long third = -1;
+        for (int i = 0; i < n; i++) {
+            long num = 0;
+            for (int j = i; j < n; j++) {
+                num = num * 10 + (s.charAt(j) - '0');
+                if (i != j && s.charAt(i) == '0') {
+                    break;
+                }
+                if (isPrime(num) && !set.contains(num)) {
+                    set.add(num);
+                    if (num > first) {
+                        third = second;
+                        second = first;
+                        first = num;
+                    } else if (num > second) {
+                        third = second;
+                        second = num;
+                    } else if (num > third) {
+                        third = num;
+                    }
+                }
+            }
+        }
+        long sum = 0;
+        if (first != -1) {
+            sum += first;
+        }
+        if (second != -1) {
+            sum += second;
+        }
+        if (third != -1) {
+            sum += third;
+        }
+        return sum;
+    }
+
+    public boolean isPrime(long num) {
+        if (num <= 1) {
+            return false;
+        }
+        if (num == 2 || num == 3) {
+            return true;
+        }
+        if (num % 2 == 0 || num % 3 == 0) {
+            return false;
+        }
+        for (long i = 5; i * i <= num; i += 6) {
+            if (num % i == 0 || num % (i + 2) == 0) {
+                return false;
+            }
+        }
+        return true;
+    }
+}

src/main/java/g3501_3600/s3556_sum_of_largest_prime_substrings/readme.md

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+3556\. Sum of Largest Prime Substrings
+
+Medium
+
+Given a string `s`, find the sum of the **3 largest unique prime numbers** that can be formed using any of its ****substring****.
+
+Return the **sum** of the three largest unique prime numbers that can be formed. If fewer than three exist, return the sum of **all** available primes. If no prime numbers can be formed, return 0.
+
+**Note:** Each prime number should be counted only **once**, even if it appears in **multiple** substrings. Additionally, when converting a substring to an integer, any leading zeros are ignored.
+
+**Example 1:**
+
+**Input:** s = "12234"
+
+**Output:** 1469
+
+**Explanation:**
+
+*   The unique prime numbers formed from the substrings of `"12234"` are 2, 3, 23, 223, and 1223.
+*   The 3 largest primes are 1223, 223, and 23. Their sum is 1469.
+
+**Example 2:**
+
+**Input:** s = "111"
+
+**Output:** 11
+
+**Explanation:**
+
+*   The unique prime number formed from the substrings of `"111"` is 11.
+*   Since there is only one prime number, the sum is 11.
+
+**Constraints:**
+
+*   `1 <= s.length <= 10`
+*   `s` consists of only digits.

src/main/java/g3501_3600/s3557_find_maximum_number_of_non_intersecting_substrings/Solution.java

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+package g3501_3600.s3557_find_maximum_number_of_non_intersecting_substrings;
+
+// #Medium #String #Hash_Table #Dynamic_Programming #Greedy
+// #2025_05_27_Time_15_ms_(84.54%)_Space_45.82_MB_(91.39%)
+
+import java.util.Arrays;
+
+public class Solution {
+    public int maxSubstrings(String s) {
+        int[] prev = new int[26];
+        int r = 0;
+        Arrays.fill(prev, -1);
+        for (int i = 0; i < s.length(); ++i) {
+            int j = s.charAt(i) - 'a';
+            if (prev[j] != -1 && i - prev[j] + 1 >= 4) {
+                ++r;
+                Arrays.fill(prev, -1);
+            } else if (prev[j] == -1) {
+                prev[j] = i;
+            }
+        }
+        return r;
+    }
+}

src/main/java/g3501_3600/s3557_find_maximum_number_of_non_intersecting_substrings/readme.md

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+3557\. Find Maximum Number of Non Intersecting Substrings
+
+Medium
+
+You are given a string `word`.
+
+Return the **maximum** number of non-intersecting ****substring**** of word that are at **least** four characters long and start and end with the same letter.
+
+**Example 1:**
+
+**Input:** word = "abcdeafdef"
+
+**Output:** 2
+
+**Explanation:**
+
+The two substrings are `"abcdea"` and `"fdef"`.
+
+**Example 2:**
+
+**Input:** word = "bcdaaaab"
+
+**Output:** 1
+
+**Explanation:**
+
+The only substring is `"aaaa"`. Note that we cannot **also** choose `"bcdaaaab"` since it intersects with the other substring.
+
+**Constraints:**
+
+*   <code>1 <= word.length <= 2 * 10<sup>5</sup></code>
+*   `word` consists only of lowercase English letters.

src/main/java/g3501_3600/s3558_number_of_ways_to_assign_edge_weights_i/Solution.java

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+package g3501_3600.s3558_number_of_ways_to_assign_edge_weights_i;
+
+// #Medium #Math #Tree #Depth_First_Search #2025_05_27_Time_12_ms_(100.00%)_Space_106.62_MB_(76.01%)
+
+public class Solution {
+    private static int mod = (int) 1e9 + 7;
+    private long[] pow2 = new long[100001];
+
+    public int assignEdgeWeights(int[][] edges) {
+        if (pow2[0] == 0) {
+            pow2[0] = 1;
+            for (int i = 1; i < pow2.length; i++) {
+                pow2[i] = (pow2[i - 1] << 1) % mod;
+            }
+        }
+        int n = edges.length + 1;
+        int[] adj = new int[n + 1];
+        int[] degrees = new int[n + 1];
+        for (int[] edge : edges) {
+            int u = edge[0];
+            int v = edge[1];
+            adj[u] += v;
+            adj[v] += u;
+            degrees[u]++;
+            degrees[v]++;
+        }
+        int[] que = new int[n];
+        int write = 0;
+        int read = 0;
+        for (int i = 2; i <= n; ++i) {
+            if (degrees[i] == 1) {
+                que[write++] = i;
+            }
+        }
+        int distance = 0;
+        while (read < write) {
+            distance++;
+            int size = write - read;
+            while (size-- > 0) {
+                int v = que[read++];
+                int u = adj[v];
+                adj[u] -= v;
+                if (--degrees[u] == 1 && u != 1) {
+                    que[write++] = u;
+                }
+            }
+        }
+        return (int) pow2[distance - 1];
+    }
+}

src/main/java/g3501_3600/s3558_number_of_ways_to_assign_edge_weights_i/readme.md

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+3558\. Number of Ways to Assign Edge Weights I
+
+Medium
+
+There is an undirected tree with `n` nodes labeled from 1 to `n`, rooted at node 1. The tree is represented by a 2D integer array `edges` of length `n - 1`, where <code>edges[i] = [u<sub>i</sub>, v<sub>i</sub>]</code> indicates that there is an edge between nodes <code>u<sub>i</sub></code> and <code>v<sub>i</sub></code>.
+
+Initially, all edges have a weight of 0. You must assign each edge a weight of either **1** or **2**.
+
+The **cost** of a path between any two nodes `u` and `v` is the total weight of all edges in the path connecting them.
+
+Select any one node `x` at the **maximum** depth. Return the number of ways to assign edge weights in the path from node 1 to `x` such that its total cost is **odd**.
+
+Since the answer may be large, return it **modulo** <code>10<sup>9</sup> + 7</code>.
+
+**Note:** Ignore all edges **not** in the path from node 1 to `x`.
+
+**Example 1:**
+
+![](https://assets.leetcode.com/uploads/2025/03/23/screenshot-2025-03-24-at-060006.png)
+
+**Input:** edges = [[1,2]]
+
+**Output:** 1
+
+**Explanation:**
+
+*   The path from Node 1 to Node 2 consists of one edge (`1 → 2`).
+*   Assigning weight 1 makes the cost odd, while 2 makes it even. Thus, the number of valid assignments is 1.
+
+**Example 2:**
+
+![](https://assets.leetcode.com/uploads/2025/03/23/screenshot-2025-03-24-at-055820.png)
+
+**Input:** edges = [[1,2],[1,3],[3,4],[3,5]]
+
+**Output:** 2
+
+**Explanation:**
+
+*   The maximum depth is 2, with nodes 4 and 5 at the same depth. Either node can be selected for processing.
+*   For example, the path from Node 1 to Node 4 consists of two edges (`1 → 3` and `3 → 4`).
+*   Assigning weights (1,2) or (2,1) results in an odd cost. Thus, the number of valid assignments is 2.
+
+**Constraints:**
+
+*   <code>2 <= n <= 10<sup>5</sup></code>
+*   `edges.length == n - 1`
+*   <code>edges[i] == [u<sub>i</sub>, v<sub>i</sub>]</code>
+*   <code>1 <= u<sub>i</sub>, v<sub>i</sub> <= n</code>
+*   `edges` represents a valid tree.

src/main/java/g3501_3600/s3559_number_of_ways_to_assign_edge_weights_ii/Solution.java

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+package g3501_3600.s3559_number_of_ways_to_assign_edge_weights_ii;
+
+// #Hard #Array #Dynamic_Programming #Math #Tree #Depth_First_Search
+// #2025_05_27_Time_138_ms_(64.66%)_Space_133.20_MB_(11.56%)
+
+import java.util.ArrayList;
+import java.util.List;
+
+public class Solution {
+    private static final int MOD = 1000000007;
+    private List<List<Integer>> adj;
+    private int[] level;
+    private int[][] jumps;
+
+    private void mark(int node, int par) {
+        for (int neigh : adj.get(node)) {
+            if (neigh == par) {
+                continue;
+            }
+            level[neigh] = level[node] + 1;
+            jumps[neigh][0] = node;
+            mark(neigh, node);
+        }
+    }
+
+    public int lift(int u, int diff) {
+        while (diff > 0) {
+            int rightmost = diff ^ (diff & (diff - 1));
+            int jump = (int) (Math.log(rightmost) / Math.log(2));
+            u = jumps[u][jump];
+            diff -= rightmost;
+        }
+        return u;
+    }
+
+    private int findLca(int u, int v) {
+        if (level[u] > level[v]) {
+            int temp = u;
+            u = v;
+            v = temp;
+        }
+        v = lift(v, level[v] - level[u]);
+        if (u == v) {
+            return u;
+        }
+        for (int i = jumps[0].length - 1; i >= 0; i--) {
+            if (jumps[u][i] != jumps[v][i]) {
+                u = jumps[u][i];
+                v = jumps[v][i];
+            }
+        }
+        return jumps[u][0];
+    }
+
+    private int findDist(int a, int b) {
+
+        return level[a] + level[b] - 2 * level[findLca(a, b)];
+    }
+
+    public int[] assignEdgeWeights(int[][] edges, int[][] queries) {
+        int n = edges.length + 1;
+        adj = new ArrayList<>();
+        level = new int[n];
+        for (int i = 0; i < n; i++) {
+            adj.add(new ArrayList<>());
+        }
+        for (int[] i : edges) {
+            adj.get(i[0] - 1).add(i[1] - 1);
+            adj.get(i[1] - 1).add(i[0] - 1);
+        }
+        int m = (int) (Math.ceil(Math.log(n - 1.0) / Math.log(2))) + 1;
+        jumps = new int[n][m];
+        mark(0, -1);
+        for (int j = 1; j < m; j++) {
+            for (int i = 0; i < n; i++) {
+                int p = jumps[i][j - 1];
+                jumps[i][j] = jumps[p][j - 1];
+            }
+        }
+        int[] pow = new int[n + 1];
+        pow[0] = 1;
+        for (int i = 1; i <= n; i++) {
+            pow[i] = (pow[i - 1] * 2) % MOD;
+        }
+        int q = queries.length;
+        int[] ans = new int[q];
+        for (int i = 0; i < q; i++) {
+            int d = findDist(queries[i][0] - 1, queries[i][1] - 1);
+            ans[i] = d > 0 ? pow[d - 1] : 0;
+        }
+        return ans;
+    }
+}