feat: add solution for maximum product subarray

Author: bujosa

src/medium/maximum_product_subarray.rs

@@ -0,0 +1,21 @@
+#![allow(dead_code)]
+pub fn max_product(nums: Vec<i32>) -> i32 {
+    let mut res = *nums.iter().max().unwrap();
+    let (mut cur_min, mut cur_max) = (1, 1);
+
+    for &n in nums.iter() {
+        let tmp = cur_max * n;
+        cur_max = std::cmp::max(std::cmp::max(n * cur_max, n * cur_min), n);
+        cur_min = std::cmp::min(std::cmp::min(tmp, n * cur_min), n);
+        res = std::cmp::max(std::cmp::max(res, cur_max), cur_min);
+    }
+
+    res
+}
+
+#[test]
+fn test_max_product() {
+    assert_eq!(max_product(vec![2, 3, -2, 4]), 6);
+    assert_eq!(max_product(vec![-2, 0, -1]), 0);
+    assert_eq!(max_product(vec![-2]), -2);
+}