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[LeetCode] Modify Graph Edge Weights 2023-05-21|PSLeetCode|Problem Solving-Dijkstra

You are given an undirected weighted connected graph containing n nodes labeled from 0 to n - 1, and an integer array edges where edges[i] = [ai, bi, wi] indicates that there is an edge between nodes ai and bi with weight wi.

Some edges have a weight of -1 (wi = -1), while others have a positive weight (wi > 0).

Your task is to modify all edges with a weight of -1 by assigning them positive integer values in the range [1, 2 * 109] so that the shortest distance between the nodes source and destination becomes equal to an integer target. If there are multiple modifications that make the shortest distance between source and destination equal to target, any of them will be considered correct.

Return an array containing all edges (even unmodified ones) in any order if it is possible to make the shortest distance from source to destination equal to target, or an empty array if it’s impossible.

Note: You are not allowed to modify the weights of edges with initial positive weights.

[LeetCode] Find the Punishment Number of an Integer 2023-05-21|PSLeetCode|Problem Solving-Back Tracking

2698. Find the Punishment Number of an Integer

Given a positive integer n, return the punishment number of n.

The punishment number of n is defined as the sum of the squares of all integers i such that:

1 <= i <= n

The decimal representation of i * i can be partitioned into contiguous substrings such that the sum of the integer values of these substrings equals i.

[LeetCode] Lexicographically Smallest Palindrome 2023-05-21|PSLeetCode|Problem Solving-Two Pointer

2697. Lexicographically Smallest Palindrome

You are given a string s consisting of lowercase English letters, and you are allowed to perform operations on it. In one operation, you can replace a character in s with another lowercase English letter.

Your task is to make s a palindrome with the minimum number of operations possible. If there are multiple palindromes that can be made using the minimum number of operations, make the lexicographically smallest one.

A string a is lexicographically smaller than a string b (of the same length) if in the first position where a and b differ, string a has a letter that appears earlier in the alphabet than the corresponding letter in b.

Return the resulting palindrome string.

[LeetCode] Minimum String Length After Removing Substrings 2023-05-21|PSLeetCode|Problem Solving-Monotonic Stack

2696. Minimum String Length After Removing Substrings

You are given a string s consisting only of uppercase English letters.

You can apply some operations to this string where, in one operation, you can remove any occurrence of one of the substrings "AB" or "CD" from s.

Return the minimum possible length of the resulting string that you can obtain.

Note that the string concatenates after removing the substring and could produce new "AB" or "CD" substrings.