Update 0063.不同路径II.md

problems/0063.不同路径II.md

@@ -493,6 +493,34 @@ impl Solution {
 }
 ```
 
+空间优化：
+
+```rust
+impl Solution {
+    pub fn unique_paths_with_obstacles(obstacle_grid: Vec<Vec<i32>>) -> i32 {
+        let mut dp = vec![0; obstacle_grid[0].len()];
+        for (i, &v) in obstacle_grid[0].iter().enumerate() {
+            if v == 0 {
+                dp[i] = 1;
+            } else {
+                break;
+            }
+        }
+        for rows in obstacle_grid.iter().skip(1) {
+            for j in 0..rows.len() {
+                if rows[j] == 1 {
+                    dp[j] = 0;
+                    continue;
+                } else if j != 0 {
+                    dp[j] += dp[j - 1];
+                }
+            }
+        }
+        dp.pop().unwrap()
+    }
+}
+```
+
 ### C
 
 ```c