src/bin/product-of-array-except-self.rs

Author: bestgopher

src/bin/product-of-array-except-self.rs

@@ -0,0 +1,45 @@
+fn main() {
+    println!("{:?}", Solution::product_except_self(vec![1, 2, 3, 4]));
+}
+
+struct Solution;
+
+impl Solution {
+    /// 常规解法
+    pub fn product_except_self1(nums: Vec<i32>) -> Vec<i32> {
+        let sum = nums.iter().fold(1, |x, y| x * *y);
+
+        nums.iter().fold(vec![], |mut x, y| {
+            x.push(sum / (*y));
+            x
+        })
+    }
+
+    /// 左右乘积，某个位置的积 == 左边*右边
+    pub fn product_except_self(nums: Vec<i32>) -> Vec<i32> {
+        let mut v = Vec::with_capacity(nums.len());
+        for i in 0..nums.len() {
+            if i == 0 {
+                v.push(1);
+            } else if i == 1 {
+                v.push(nums[i - 1]);
+            } else {
+                v.push(nums[i - 1] * v[i - 1]);
+            }
+        }
+
+        let mut x = 1;
+
+        for i in (0..nums.len()).rev() {
+            if i == nums.len() - 1 {
+                x = nums[i];
+                continue;
+            } else {
+                v[i] = v[i] * x;
+                x *= nums[i];
+            }
+        }
+
+        v
+    }
+}