1009. 十进制整数的反码

src/main.rs

@@ -1,44 +1,20 @@
+use std::ops::BitXor;
+
 struct Solution;
 mod arr;
 
 impl Solution {
-    pub fn number_of_stable_arrays(zero: i32, one: i32, limit: i32) -> i32 {
-        let md = 1e9 as i64 + 7;
-        let mut dp = vec![vec![vec![0; 2]; one as usize + 1]; zero as usize + 1];
-        for i in 1..=limit as usize {
-            if i <= one as usize {
-                dp[0][i][1] = 1;
-            }
-            if i <= zero as usize {
-                dp[i][0][0] = 1;
-            }
+    pub fn bitwise_complement(n: i32) -> i32 {
+        let mut a = 1;
+        for i in 1.. n.count_ones() + n.count_zeros() - n.leading_zeros() {
+            a |= 1 << i;
         }
-        for i in 1..=zero as usize {
-            for j in 1..=one as usize {
-                dp[i][j][0] = (((dp[i - 1][j][0] + dp[i - 1][j][1]
-                    - if i as i32 - limit - 1 >= 0 {
-                    dp[i - limit as usize - 1][j][1]
-                } else {
-                    0
-                }) as i64
-                    + md)
-                    % md) as i32;
-                dp[i][j][1] = (((dp[i][j - 1][0] + dp[i][j - 1][1]
-                    - if j as i32 - limit - 1 >= 0 {
-                    dp[i][j - limit as usize - 1][0]
-                } else {
-                    0
-                }) as i64
-                    + md)
-                    % md) as i32;
-            }
-        }
-        ((dp[zero as usize][one as usize][0] as i64 + dp[zero as usize][one as usize][1] as i64) % md) as i32
+        n.bitxor(a)
     }
 }
 
 fn main() {
-    let result = Solution::number_of_stable_arrays(39, 20, 18);
+    let result = Solution::bitwise_complement(0);
     // let result = Solution::number_of_stable_arrays(200, 200, 25);
     println!("{:?}", result);
 }