solve 334.increasing-triplet-subsequence

Author: andavid

vscode/334.increasing-triplet-subsequence.java

@@ -0,0 +1,62 @@
+/*
+ * @lc app=leetcode id=334 lang=java
+ *
+ * [334] Increasing Triplet Subsequence
+ *
+ * https://leetcode.com/problems/increasing-triplet-subsequence/description/
+ *
+ * algorithms
+ * Medium (39.55%)
+ * Likes:    971
+ * Dislikes: 96
+ * Total Accepted:    103.8K
+ * Total Submissions: 262.4K
+ * Testcase Example:  '[1,2,3,4,5]'
+ *
+ * Given an unsorted array return whether an increasing subsequence of length 3
+ * exists or not in the array.
+ *
+ * Formally the function should:
+ *
+ * Return true if there exists i, j, k
+ * such that arr[i] < arr[j] < arr[k] given 0 ≤ i < j < k ≤ n-1 else return
+ * false.
+ *
+ * Note: Your algorithm should run in O(n) time complexity and O(1) space
+ * complexity.
+ *
+ *
+ * Example 1:
+ *
+ *
+ * Input: [1,2,3,4,5]
+ * Output: true
+ *
+ *
+ *
+ * Example 2:
+ *
+ *
+ * Input: [5,4,3,2,1]
+ * Output: false
+ *
+ *
+ *
+ */
+class Solution {
+  public boolean increasingTriplet(int[] nums) {
+    int small = Integer.MAX_VALUE;
+    int big = Integer.MAX_VALUE;
+    for (int num : nums) {
+      if (num <= small) {
+        small = num;
+      } else if (num <= big) {
+        big = num;
+      } else {
+        return true;
+      }
+    }
+    return false;
+  }
+}
+