leetcode

commit 80364cba46622522bb7573ecbfd4bc246c172d70
parent 33da8f1d4dee4987f9836fbb170a9d6e62f38ce9
Author: Jack Sangdahl <jack@pngu.org>
Date:   Mon,  2 Feb 2026 21:41:18 -0700

3637. trionic array 1

Diffstat:
A
trionic_array1.c
 | 
36
++++++++++++++++++++++++++++++++++++
A
trionic_array1.py
 | 
36
++++++++++++++++++++++++++++++++++++

2 files changed, 72 insertions(+), 0 deletions(-)
diff --git a/trionic_array1.c b/trionic_array1.c
@@ -0,0 +1,36 @@
+// 3637. Trionic Array I
+#include "leetcode.h"
+
+/*
+ * you are given an integer array 'nums' of length 'n'. an array is trionic if
+ * there exist indices '0 < p < q < n - 1' such that 'nums[0 ... p]' is strictly
+ * increasing, 'nums[p ... q]' is strictly decreasing, and  'nums[q ... n - 1]'
+ * is strictly increasing. return true if 'nums' is trionic, otherwise return
+ * false.
+ */
+
+bool isTrionic(int *nums, int numsSize) {
+  if (numsSize < 4)
+    return false;
+  int trans[4][2] = {{1, 4}, {1, 2}, {3, 2}, {3, 4}};
+  int state = 0;
+  for (int i = 1; i < numsSize; i++) {
+    if (nums[i] == nums[i - 1])
+      return false;
+    int input = (nums[i] > nums[i - 1]) ? 0 : 1;
+    state = (state < 4) ? trans[state][input] : 4;
+    if (state == 4)
+      return false;
+  }
+  return state == 3;
+}
+
+int main() {
+  int n1[] = {1, 3, 5, 4, 2, 6}, n2[] = {2, 1, 3};
+  bool r1 = isTrionic(n1, ARRAY_SIZE(n1));
+  bool r2 = isTrionic(n2, ARRAY_SIZE(n2));
+  printf("%d\n", r1); // expect: 1
+  assert(r1 == true);
+  printf("%d\n", r2); // expect: 0
+  assert(r2 == false);
+}
diff --git a/trionic_array1.py b/trionic_array1.py
@@ -0,0 +1,36 @@
+# 3637. Trionic Array I
+
+"""
+you are given an integer array 'nums' of length 'n'. an array is trionic if
+there exist indices '0 < p < q < n - 1' such that 'nums[0 ... p]' is strictly
+increasing, 'nums[p ... q]' is strictly decreasing, and  'nums[q ... n - 1]'
+is strictly increasing. return true if 'nums' is trionic, otherwise return
+false.
+"""
+
+
+class Solution(object):
+    def isTrionic(self, nums):
+        """
+        :type nums: List[int]
+        :rtype: bool
+        """
+        n, i = len(nums), 0
+        while i + 1 < n and nums[i] < nums[i + 1]:
+            i += 1
+        if i == 0 or i == n - 1:
+            return False
+        p = i
+        while i + 1 < n and nums[i] > nums[i + 1]:
+            i += 1
+        if i == p or i == n - 1:
+            return False
+        while i + 1 < n and nums[i] < nums[i + 1]:
+            i += 1
+        return i == n - 1
+
+
+if __name__ == "__main__":
+    obj = Solution()
+    print(obj.isTrionic(nums=[1, 3, 5, 4, 2, 6]))
+    print(obj.isTrionic(nums=[2, 1, 3]))