LC 2601. Prime Subtraction Operation (Rust)

Author: raul-sauco

README.md

@@ -732,6 +732,7 @@ to the solution in this repository.
 | [2543. Check if Point Is Reachable][lc2543]                                                   | 🔴 Hard    | [![python](res/py.png)][lc2543py] [![rust](res/rs.png)][lc2543rs]                                     |
 | [2583. Kth Largest Sum in a Binary Tree][lc2583]                                              | 🟠 Medium  | [![rust](res/rs.png)][lc2583rs]                                                                       |
 | [2585. Number of Ways to Earn Points][lc2585]                                                 | 🔴 Hard    | [![python](res/py.png)][lc2585py] [![rust](res/rs.png)][lc2585rs]                                     |
+| [2601. Prime Subtraction Operation][lc2601]                                                   | 🟠 Medium  | [![rust](res/rs.png)][lc2601rs]                                                                       |
 | [2616. Minimize the Maximum Difference of Pairs][lc2616]                                      | 🟠 Medium  | [![rust](res/rs.png)][lc2616rs]                                                                       |
 | [2618. Check if Object Instance of Class][lc2618]                                             | 🟠 Medium  | [![js](res/js.png)][lc2618js]                                                                         |
 | [2619. Array Prototype Last][lc2619]                                                          | 🟢 Easy    | [![js](res/js.png)][lc2619js]                                                                         |
@@ -2402,6 +2403,8 @@ to the solution in this repository.
 [lc2585]: https://leetcode.com/problems/number-of-ways-to-earn-points/
 [lc2585py]: leetcode/number-of-ways-to-earn-points.py
 [lc2585rs]: leetcode/number-of-ways-to-earn-points.rs
+[lc2601]: https://leetcode.com/problems/prime-subtraction-operation/
+[lc2601rs]: leetcode/prime-subtraction-operation.rs
 [lc2616]: https://leetcode.com/problems/minimize-the-maximum-difference-of-pairs/
 [lc2616rs]: leetcode/minimize-the-maximum-difference-of-pairs.rs
 [lc2618]: https://leetcode.com/problems/check-if-object-instance-of-class/

leetcode/prime-subtraction-operation.rs

@@ -0,0 +1,78 @@
+// 2601. Prime Subtraction Operation
+// 🟠 Medium
+//
+// https://leetcode.com/problems/prime-subtraction-operation/
+//
+// Tags: Array - Math - Binary Search - Greedy - Number Theory
+
+struct Solution;
+impl Solution {
+    /// Iterate over the values from right to left, for each value, we try to find a prime we can
+    /// subtract that makes the value less than the one to the right but still greater than 0.
+    ///
+    /// Time complexity: O(n) - We iterate over all the values in the input, for each, we try to
+    /// find a prime number we can subtract iterating over a fixed number of elements.
+    /// Space complexity: O(1) - Constant extra memory used.
+    ///
+    /// Runtime 0 ms Beats 100%
+    /// Memory 2.14 MB Beats 100%
+    pub fn prime_sub_operation(nums: Vec<i32>) -> bool {
+        fn doit(state: i32, x: i32) -> Option<i32> {
+            let primes = [
+                0, 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73,
+                79, 83, 89, 97, 101, 103, 107, 109, 113, 127, 131, 137, 139, 149, 151, 157, 163,
+                167, 173, 179, 181, 191, 193, 197, 199, 211, 223, 227, 229, 233, 239, 241, 251,
+                257, 263, 269, 271, 277, 281, 283, 293, 307, 311, 313, 317, 331, 337, 347, 349,
+                353, 359, 367, 373, 379, 383, 389, 397, 401, 409, 419, 421, 431, 433, 439, 443,
+                449, 457, 461, 463, 467, 479, 487, 491, 499, 503, 509, 521, 523, 541, 547, 557,
+                563, 569, 571, 577, 587, 593, 599, 601, 607, 613, 617, 619, 631, 641, 643, 647,
+                653, 659, 661, 673, 677, 683, 691, 701, 709, 719, 727, 733, 739, 743, 751, 757,
+                761, 769, 773, 787, 797, 809, 811, 821, 823, 827, 829, 839, 853, 857, 859, 863,
+                877, 881, 883, 887, 907, 911, 919, 929, 937, 941, 947, 953, 967, 971, 977, 983,
+                991, 997,
+            ];
+            // State is the value to the right.
+            for val in primes.into_iter().map(|prime| x - prime) {
+                if val < state && val > 0 {
+                    return Some(val);
+                }
+            }
+            None
+        }
+        nums.into_iter().rev().try_fold(i32::MAX, doit).is_some()
+    }
+}
+
+// Tests.
+fn main() {
+    let tests = [
+        (vec![4, 9, 6, 10], true),
+        (vec![6, 8, 11, 12], true),
+        (vec![5, 8, 3], false),
+    ];
+    println!("\n\x1b[92m» Running {} tests...\x1b[0m", tests.len());
+    let mut success = 0;
+    for (i, t) in tests.iter().enumerate() {
+        let res = Solution::prime_sub_operation(t.0.clone());
+        if res == t.1 {
+            success += 1;
+            println!("\x1b[92m✔\x1b[95m Test {} passed!\x1b[0m", i);
+        } else {
+            println!(
+                "\x1b[31mx\x1b[95m Test {} failed expected: {:?} but got {}!!\x1b[0m",
+                i, t.1, res
+            );
+        }
+    }
+    println!();
+    if success == tests.len() {
+        println!("\x1b[30;42m✔ All tests passed!\x1b[0m")
+    } else if success == 0 {
+        println!("\x1b[31mx \x1b[41;37mAll tests failed!\x1b[0m")
+    } else {
+        println!(
+            "\x1b[31mx\x1b[95m {} tests failed!\x1b[0m",
+            tests.len() - success
+        )
+    }
+}