Merge pull request #12980 from fer2o3/kachow

feat(346): completed both challenges

2 files changed, 86 insertions, 0 deletions

diff --git a/challenge-346/benjamin-andre/rust/ch-1.rs b/challenge-346/benjamin-andre/rust/ch-1.rs
new file mode 100755
index 0000000000..9a87c5f34c
--- /dev/null
+++ b/challenge-346/benjamin-andre/rust/ch-1.rs
@@ -0,0 +1,29 @@
+#!/bin/sh
+//usr/bin/env rustc --test $0 -o kachow && ./kachow --nocapture; rm -f kachow ; exit
+
+fn longest_parenthesis(s: &str) -> usize {
+    let mut stack = vec![-1];
+    let mut max_len = 0;
+    for (i, c) in s.chars().enumerate() {
+        if c == '(' {
+            stack.push(i as i32);
+        } else {
+            stack.pop();
+            if stack.is_empty() {
+                stack.push(i as i32);
+            } else {
+                max_len = max_len.max(i as i32 - stack[stack.len() - 1]);
+            }
+        }
+    }
+    max_len as usize
+}
+
+#[test]
+fn example() {
+    assert_eq!(longest_parenthesis("(()())"), 6);
+    assert_eq!(longest_parenthesis(")()())"), 4);
+    assert_eq!(longest_parenthesis("((()))()(((("), 8);
+    assert_eq!(longest_parenthesis("))))(()("), 2);
+    assert_eq!(longest_parenthesis("()(()"), 2);
+}
diff --git a/challenge-346/benjamin-andre/rust/ch-2.rs b/challenge-346/benjamin-andre/rust/ch-2.rs
new file mode 100755
index 0000000000..634ce1cc5a
--- /dev/null
+++ b/challenge-346/benjamin-andre/rust/ch-2.rs
@@ -0,0 +1,57 @@
+#!/bin/sh
+//usr/bin/env rustc --test $0 -o kachow && ./kachow --nocapture; rm -f kachow ; exit
+fn magic_expression(s: &str, target: i32) -> Vec<String> {
+    fn eval(expr: &str) -> i32 {
+        let mut terms = Vec::new();
+        let mut current = 0;
+        let mut op = '+';
+        for c in expr.chars().chain(std::iter::once('+')) {
+            if c.is_ascii_digit() {
+                current = current * 10 + c.to_digit(10).unwrap() as i32;
+            } else {
+                let value = if op == '*' {
+                    terms.pop().unwrap() * current
+                } else {
+                    current * if op == '-' { -1 } else { 1 }
+                };
+                terms.push(value);
+                current = 0;
+                op = c;
+            }
+        }
+        terms.iter().sum()
+    }
+
+    fn generate(s: &str, pos: usize, expr: String, target: i32, result: &mut Vec<String>) {
+        if pos == s.len() {
+            if eval(&expr) == target {
+                result.push(expr);
+            }
+            return;
+        }
+        let ch = s.chars().nth(pos).unwrap();
+        if pos == 0 {
+            generate(s, pos + 1, ch.to_string(), target, result);
+        } else {
+            for &op in &['+', '-', '*'] {
+                generate(s, pos + 1, format!("{}{}{}", expr, op, ch), target, result);
+            }
+        }
+    }
+
+    let mut result = Vec::new();
+    generate(s, 0, String::new(), target, &mut result);
+    result
+}
+
+#[test]
+fn example() {
+    assert_eq!(magic_expression("123", 6), vec!["1*2*3", "1+2+3"]);
+    assert_eq!(magic_expression("105", 5), vec!["1*0+5", "10-5"]);
+    assert_eq!(magic_expression("232", 8), vec!["2*3+2", "2+3*2"]);
+    assert_eq!(magic_expression("1234", 10), vec!["1*2*3+4", "1+2+3+4"]);
+    assert_eq!(
+        magic_expression("1001", 2),
+        vec!["1+0*0+1", "1+0+0+1", "1+0-0+1", "1-0*0+1", "1-0+0+1", "1-0-0+1"]
+    );
+}