Array problem

Author: Tuhin-thinks

Arrays/sorted_triplet.py

@@ -0,0 +1,74 @@
+# Problem source: https://practice.geeksforgeeks.org/problems/sorted-subsequence-of-size-3/1
+# Sorted subsequence of size 3
+
+from collections import defaultdict
+
+
+class Solution:
+    def find3number(self, A, n):
+
+        max_a = defaultdict(lambda: -1)
+        min_a = defaultdict(lambda: -1)
+        max_e = n - 1
+        min_e = 0
+
+        # for min
+        for i in range(n):
+            e = A[i]
+            if e <= A[min_e]:
+                min_e = i
+                min_a[i] = -1
+            else:
+                min_a[i] = min_e
+
+        for j in range(n - 1, -1, -1):
+            e = A[j]
+            if e >= A[max_e]:
+                max_e = j
+                max_a[j] = -1
+            else:
+                max_a[j] = max_e
+
+        for i in range(n):
+            if min_a[i] != -1 and max_a[i] != -1:
+                seq = (A[min_a[i]], A[i], A[max_a[i]])
+                return seq
+
+        return []
+
+
+# {
+# Driver Code Starts
+# Initial Template for Python 3
+
+import sys
+
+sys.setrecursionlimit(100000)
+
+
+def isSubSeq(arr, lis, n, m):
+    if m == 0:
+        return True
+    if n == 0:
+        return False
+    if arr[n - 1] == lis[m - 1]:
+        return isSubSeq(arr, lis, n - 1, m - 1)
+    return isSubSeq(arr, lis, n - 1, m)
+
+
+t = int(input())
+for _ in range(t):
+    n = int(input())
+    arr = list(map(int, input().strip().split()))
+    lis = Solution().find3number(arr, n)
+    # print(lis)
+    # print(isSubSeq(arr, lis, n, len(lis)))
+    if len(lis) != 0 and len(lis) != 3:
+        print(-1)
+        continue
+    if len(lis) == 0:
+        print(0)
+    elif lis[0] < lis[1] and lis[1] < lis[2] and isSubSeq(arr, lis, n, len(lis)):
+        print(1)
+    else:
+        print(-1)