2044. 统计按位或能得到最大值的子集数目

src/main.rs

@@ -1,37 +1,19 @@
 struct Solution;
 impl Solution {
-    pub fn count_hill_valley(nums: Vec<i32>) -> i32 {
-        let mut down = false;
-        for i in 1..nums.len() {
-            if nums[i] != nums[0]{
-                down = nums[i] < nums[0];
-                break;
+    pub fn count_max_or_subsets(nums: Vec<i32>) -> i32 {
+        let max_or = nums.iter().fold(0, |acc, &x| acc | x);
+        let mut dp = vec![0;1<<nums.len()];
+        for i in 0..nums.len() {
+            for j in (1<<i)..(1<<(i+1)) {
+                dp[j] = dp[j - (1<<i)] | nums[i];
             }
         }
-        let mut ans = 0;
-        for i in 2..nums.len() {
-            if nums[i] == nums[i-1]
-            {
-                continue;
-            }
-            if down && nums[i] >nums[i-1]
-            {
-                ans += 1;
-                down = false;
-                continue;
-            }
-            if !down && nums[i] < nums[i-1] {
-                ans += 1;
-                down = true;
-                continue;
-            }
-        }
-        ans
+        dp.iter().filter(|x| **x == max_or ).count() as i32
     }
 }
 
 fn main() {
-    let sl = Solution::count_hill_valley(vec![6,6,5,5,4,1]);
+    let sl = Solution::count_max_or_subsets(vec![3,2,1,5]);
     println!("{}", sl);
 }