20240101 Finished

src/solution/mod.rs

@@ -11,3 +11,4 @@ mod s0912_sort_an_array;
 mod s1276_number_of_burgers_with_no_waste_of_ingredients;
 mod s0006_zigzag_conversion;
 mod s0007_reverse_integer;
+mod s0004_median_of_two_sorted_arrays;

src/solution/s0004_median_of_two_sorted_arrays.rs

@@ -0,0 +1,90 @@
+/**
+ * [4] Median of Two Sorted Arrays
+ *
+ * Given two sorted arrays nums1 and nums2 of size m and n respectively, return the median of the two sorted arrays.
+ * The overall run time complexity should be O(log (m+n)).
+ *  
+ * <strong class="example">Example 1:
+ *
+ * Input: nums1 = [1,3], nums2 = [2]
+ * Output: 2.00000
+ * Explanation: merged array = [1,2,3] and median is 2.
+ *
+ * <strong class="example">Example 2:
+ *
+ * Input: nums1 = [1,2], nums2 = [3,4]
+ * Output: 2.50000
+ * Explanation: merged array = [1,2,3,4] and median is (2 + 3) / 2 = 2.5.
+ *
+ *  
+ * Constraints:
+ *
+ * 	nums1.length == m
+ * 	nums2.length == n
+ * 	0 <= m <= 1000
+ * 	0 <= n <= 1000
+ * 	1 <= m + n <= 2000
+ * 	-10^6 <= nums1[i], nums2[i] <= 10^6
+ *
+ */
+pub struct Solution {}
+
+// problem: https://leetcode.cn/problems/median-of-two-sorted-arrays/
+// discuss: https://leetcode.cn/problems/median-of-two-sorted-arrays/discuss/?currentPage=1&orderBy=most_votes&query=
+
+// submission codes start here
+
+use std::cmp::min;
+
+impl Solution {
+    pub fn find_median_sorted_arrays(nums1: Vec<i32>, nums2: Vec<i32>) -> f64 {
+        let len1 = nums1.len() as i32;
+        let len2 = nums2.len() as i32;
+        let left = (len1 + len2 + 1) / 2 ;
+        let right = (len1 + len2 + 2) / 2;
+
+        (Solution::get_k_th(&nums1, 0, len1 - 1, &nums2, 0, len2 - 1, left) as f64 +
+            Solution::get_k_th(&nums1, 0, len1 - 1, &nums2, 0, len2 - 1, right) as f64) * 0.5
+    }
+
+    fn get_k_th(nums1: &Vec<i32>, start1: i32, end1: i32,
+                nums2: &Vec<i32>, start2: i32, end2: i32, k: i32) -> i32 {
+        let len1 = end1 + 1 - start1;
+        let len2 = end2 + 1 - start2;
+
+        if len1 > len2 {
+            return Solution::get_k_th(nums2, start2, end2, nums1, start1, end1, k);
+        }
+
+        if len1 == 0 {
+            return nums2[(start2 + k - 1) as usize];
+        }
+
+        if k == 1 {
+            return min(nums1[start1 as usize], nums2[start2 as usize]);
+        }
+
+        let i = start1 + min(len1, k / 2) - 1;
+        let j = start2 + min(len2, k / 2) - 1;
+
+        return if nums1[i as usize] > nums2[j as usize] {
+            Solution::get_k_th(nums1, start1, end1, nums2, j + 1, end2, k - (j - start2 + 1))
+        } else {
+            Solution::get_k_th(nums1, i + 1, end1, nums2, start2, end2, k - (i - start1 + 1))
+        }
+    }
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_4() {
+        assert_eq!(2.0, Solution::find_median_sorted_arrays(vec![1, 3], vec![2]));
+        assert_eq!(2.5, Solution::find_median_sorted_arrays(vec![1, 2], vec![3, 4]));
+        assert_eq!(2.0, Solution::find_median_sorted_arrays(vec![2], vec![]));
+    }
+}