add problem and discuss link to existing solutions

Author: songyzh

src/solution/s0001_two_sum.rs

@@ -18,6 +18,9 @@
  */
 pub struct Solution {}
 
+// problem: https://leetcode.com/problems/two-sum/
+// discuss: https://leetcode.com/problems/two-sum/discuss/?currentPage=1&orderBy=most_votes&query=
+
 // submission codes start here
 
 use std::collections::HashMap;

src/solution/s0002_add_two_numbers.rs

@@ -19,6 +19,9 @@
 pub struct Solution {}
 use crate::util::linked_list::{to_list, ListNode};
 
+// problem: https://leetcode.com/problems/add-two-numbers/
+// discuss: https://leetcode.com/problems/add-two-numbers/discuss/?currentPage=1&orderBy=most_votes&query=
+
 // submission codes start here
 
 impl Solution {

src/solution/s0003_longest_substring_without_repeating_characters.rs

@@ -12,6 +12,9 @@
  */
 pub struct Solution {}
 
+// problem: https://leetcode.com/problems/longest-substring-without-repeating-characters/
+// discuss: https://leetcode.com/problems/longest-substring-without-repeating-characters/discuss/?currentPage=1&orderBy=most_votes&query=
+
 // submission codes start here
 
 impl Solution {

src/solution/s0004_median_of_two_sorted_arrays.rs

@@ -28,6 +28,9 @@
  */
 pub struct Solution {}
 
+// problem: https://leetcode.com/problems/median-of-two-sorted-arrays/
+// discuss: https://leetcode.com/problems/median-of-two-sorted-arrays/discuss/?currentPage=1&orderBy=most_votes&query=
+
 // submission codes start here
 
 // TODO: nth slice

src/solution/s0005_longest_palindromic_substring.rs

@@ -21,6 +21,9 @@
  */
 pub struct Solution {}
 
+// problem: https://leetcode.com/problems/longest-palindromic-substring/
+// discuss: https://leetcode.com/problems/longest-palindromic-substring/discuss/?currentPage=1&orderBy=most_votes&query=
+
 // submission codes start here
 
 impl Solution {

src/solution/s0006_zigzag_conversion.rs

@@ -38,6 +38,9 @@
  */
 pub struct Solution {}
 
+// problem: https://leetcode.com/problems/zigzag-conversion/
+// discuss: https://leetcode.com/problems/zigzag-conversion/discuss/?currentPage=1&orderBy=most_votes&query=
+
 // submission codes start here
 
 impl Solution {

src/solution/s0007_reverse_integer.rs

@@ -30,6 +30,9 @@
  */
 pub struct Solution {}
 
+// problem: https://leetcode.com/problems/reverse-integer/
+// discuss: https://leetcode.com/problems/reverse-integer/discuss/?currentPage=1&orderBy=most_votes&query=
+
 // submission codes start here
 impl Solution {
     pub fn reverse(x: i32) -> i32 {

src/solution/s0008_string_to_integer_atoi.rs

@@ -61,6 +61,9 @@
  */
 pub struct Solution {}
 
+// problem: https://leetcode.com/problems/string-to-integer-atoi/
+// discuss: https://leetcode.com/problems/string-to-integer-atoi/discuss/?currentPage=1&orderBy=most_votes&query=
+
 // submission codes start here
 
 impl Solution {

src/solution/s0009_palindrome_number.rs

@@ -33,6 +33,9 @@
  */
 pub struct Solution {}
 
+// problem: https://leetcode.com/problems/palindrome-number/
+// discuss: https://leetcode.com/problems/palindrome-number/discuss/?currentPage=1&orderBy=most_votes&query=
+
 // submission codes start here
 
 // TODO: not optimal, we only have to revert half of the string

src/solution/s0010_regular_expression_matching.rs

@@ -69,6 +69,9 @@
  */
 pub struct Solution {}
 
+// problem: https://leetcode.com/problems/regular-expression-matching/
+// discuss: https://leetcode.com/problems/regular-expression-matching/discuss/?currentPage=1&orderBy=most_votes&query=
+
 // submission codes start here
 
 // TODO: NFA