feat: 🎸 add leetcode solution 1. 49. 128. 217 238. 242

Author: dirk122119

leet code/238. Product of Array Except Self/solution

@@ -0,0 +1,52 @@
+struct Solution;
+
+impl Solution {
+    pub fn product_except_self(nums: Vec<i32>) -> Vec<i32> {
+        //preProduct * sufProduct
+        // O(n)+O(n)
+        let mut product = 1;
+        let mut re_vec = vec![1;nums.len()];
+        //get every item preProduct
+        //before [1,2,3,4] return [1,1,1,1]
+        //1. i=0 product = 1*1 return [1,1*1,1,1]
+        //2. i=1 product = 1*2 return [1,1,1*2,1]
+        //3. i=2 product = 2*3 return [1,1,2,1*6]
+        //after  [1,2,3,4] return [1,1,2,6]
+        for i in 0..nums.len()-1{
+            product=product*nums[i];
+            re_vec[i+1]=product;
+        }
+        //get every item sufProduct
+        //before [1,2,3,4] return [1,1,2,6]
+        //1. i=3 product = 1*4 return [1,1,2*4,6]
+        //2. i=2 product = 4*3 return [1,1*12,8,6]
+        //3. i=1 product = 12*1 return [1*24,12,8,6]
+        //after  [1,2,3,4] return [24,12,8,6]
+        product = 1;
+        for i in (1..nums.len()).rev(){
+            product = product*nums[i];
+            re_vec[i-1] = product*re_vec[i-1];
+        }
+        re_vec
+    }
+}
+
+fn main() {
+    let nums = vec![1, 2, 3, 4];
+    let result = Solution::product_except_self(nums);
+    println!("Product except self: {:?}", result);
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_product_except_self() {
+        assert_eq!(Solution::product_except_self(vec![1, 2, 3, 4]), vec![24, 12, 8, 6]);
+        assert_eq!(Solution::product_except_self(vec![4, 3, 2, 1]), vec![6, 8, 12, 24]);
+        assert_eq!(Solution::product_except_self(vec![2, 3, 4, 5]), vec![60, 40, 30, 24]);
+        assert_eq!(Solution::product_except_self(vec![1, 2]), vec![2, 1]);
+        assert_eq!(Solution::product_except_self(vec![10, 3, 5, 6, 2]), vec![180, 600, 360, 300, 900]);
+    }
+}