2210. 统计数组中峰和谷的数量

src/main.rs

@@ -1,30 +1,37 @@
 struct Solution;
 impl Solution {
-    pub fn max_subarrays(n: i32, mut conflicting_pairs: Vec<Vec<i32>>) -> i64 {
-        let mut arr: Vec<Vec<i32>> = vec![vec![]; (n + 1) as usize];
-        for pair in conflicting_pairs.iter_mut() {
-            if pair[0] > pair[1] {
-                pair.swap(0, 1);
+    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;
             }
-            arr[pair[0] as usize].push(pair[1]);
         }
-        let mut ans: i64 = 0;
-        let mut extra: Vec<i64> = vec![0; (n + 2) as usize];
-        let mut b: Vec<i64> = vec![(n + 1) as i64; (n + 1) as usize];
-        for i in (1..=n as usize).rev() {
-            b.extend(arr[i].iter().map(|&x| x as i64));
-            b.sort_unstable();
-            b.truncate(2);
-
-            ans += (b[0] as i64) - (i as i64);
-            extra[b[0] as usize] += b[1] - b[0];
+        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 + *extra.iter().max().unwrap() as i64
+        ans
     }
 }
 
 fn main() {
-    let sl = Solution::max_subarrays(5, vec![vec![1, 2], vec![2, 5], vec![3, 5]]);
+    let sl = Solution::count_hill_valley(vec![6,6,5,5,4,1]);
     println!("{}", sl);
 }