feat: 2025-10-28打卡

2025-10-28 15:52:13 +08:00
parent fc82d7eb10
commit 2fa03ec244
13 changed files with 486 additions and 6 deletions
--- a/162.find-peak-element.java
+++ b/162.find-peak-element.java
@@ -0,0 +1,47 @@
+/*
+ * @lc app=leetcode id=162 lang=java
+ *
+ * [162] Find Peak Element
+ */
+
+// @lc code=start
+class Solution {
+    public int findPeakElement(int[] nums) {
+        int l = 0, r = nums.length-1, m;
+        while(l <= r) {
+            m = l + (r-l)/2;
+            if(isPeak(m, nums)) {
+                return m;
+            } else if(isIncreasing(m, nums)) {
+                l = m + 1;
+            } else {
+                r = m - 1;
+            }
+        }
+        throw new RuntimeException("input is not valid");
+    }
+
+    private boolean isPeak(int i, int[] nums) {
+        boolean left = false, right = false;
+        if(i == 0) {
+            left = true;
+        } else {
+            left = nums[i] > nums[i-1];
+        }
+        if(i == nums.length-1) {
+            right = true;
+        } else {
+            right = nums[i] > nums[i+1];
+        }
+        return left && right;
+    }
+
+    private boolean isIncreasing(int i, int[] nums) {
+        if(isPeak(i, nums)) {
+            throw new RuntimeException("unexpected input");
+        }
+        return i>0?nums[i]-nums[i-1]>0:nums[i+1]-nums[i]>0;
+    }
+}
+// @lc code=end
+