1567. Maximum Length of Subarray With Positive Product: AC

Author: tan-wei

src/solution/mod.rs

@@ -1181,3 +1181,4 @@ mod s1561_maximum_number_of_coins_you_can_get;
 mod s1562_find_latest_group_of_size_m;
 mod s1563_stone_game_v;
 mod s1566_detect_pattern_of_length_m_repeated_k_or_more_times;
+mod s1567_maximum_length_of_subarray_with_positive_product;

src/solution/s1567_maximum_length_of_subarray_with_positive_product.rs

@@ -0,0 +1,102 @@
+/**
+ * [1567] Maximum Length of Subarray With Positive Product
+ *
+ * Given an array of integers nums, find the maximum length of a subarray where the product of all its elements is positive.
+ * A subarray of an array is a consecutive sequence of zero or more values taken out of that array.
+ * Return the maximum length of a subarray with positive product.
+ *  
+ * Example 1:
+ *
+ * Input: nums = [1,-2,-3,4]
+ * Output: 4
+ * Explanation: The array nums already has a positive product of 24.
+ *
+ * Example 2:
+ *
+ * Input: nums = [0,1,-2,-3,-4]
+ * Output: 3
+ * Explanation: The longest subarray with positive product is [1,-2,-3] which has a product of 6.
+ * Notice that we cannot include 0 in the subarray since that'll make the product 0 which is not positive.
+ * Example 3:
+ *
+ * Input: nums = [-1,-2,-3,0,1]
+ * Output: 2
+ * Explanation: The longest subarray with positive product is [-1,-2] or [-2,-3].
+ *
+ *  
+ * Constraints:
+ *
+ * 	1 <= nums.length <= 10^5
+ * 	-10^9 <= nums[i] <= 10^9
+ *
+ */
+pub struct Solution {}
+
+// problem: https://leetcode.com/problems/maximum-length-of-subarray-with-positive-product/
+// discuss: https://leetcode.com/problems/maximum-length-of-subarray-with-positive-product/discuss/?currentPage=1&orderBy=most_votes&query=
+
+// submission codes start here
+
+impl Solution {
+    pub fn get_max_len(nums: Vec<i32>) -> i32 {
+        let n = nums.len();
+        if n == 0 {
+            return 0;
+        }
+
+        let mut pos = if nums[0] > 0 { 1 } else { 0 };
+        let mut result = pos;
+
+        let mut neg = if nums[0] < 0 { 1 } else { 0 };
+
+        for i in 1..n {
+            let curr = nums[i];
+            if curr == 0 {
+                pos = 0;
+                neg = 0;
+            } else {
+                let next_neg = if neg > 0 { neg + 1 } else { 0 };
+                let next_pos = pos + 1;
+                pos = if curr < 0 { next_neg } else { next_pos };
+                neg = if curr < 0 { next_pos } else { next_neg };
+            }
+            result = std::cmp::max(result, pos);
+        }
+
+        result
+    }
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_1567_example_1() {
+        let nums = vec![1, -2, -3, 4];
+
+        let result = 4;
+
+        assert_eq!(Solution::get_max_len(nums), result);
+    }
+
+    #[test]
+    fn test_1567_example_2() {
+        let nums = vec![0, 1, -2, -3, -4];
+
+        let result = 3;
+
+        assert_eq!(Solution::get_max_len(nums), result);
+    }
+
+    #[test]
+    fn test_1567_example_3() {
+        let nums = vec![-1, -2, -3, 0, 1];
+
+        let result = 2;
+
+        assert_eq!(Solution::get_max_len(nums), result);
+    }
+}