array problems

Author: Tuhin-thinks

Arrays/largest_subarray_0_sum.py

@@ -0,0 +1,26 @@
+# Problem source: https://practice.geeksforgeeks.org/problems/largest-subarray-with-0-sum/1
+# Max sub array with 0 sum
+
+class Solution:
+    def maxLen(self, n, arr):
+        sum_dict = {-1: 0}
+        pre_sum = 0
+        max_arr_len = 0
+        for idx, el in enumerate(arr):
+            pre_sum += el
+            if pre_sum in sum_dict:
+                max_arr_len = max(max_arr_len, idx - sum_dict[pre_sum])
+            else:
+                sum_dict[pre_sum] = idx
+        return max_arr_len
+
+
+# {
+# Driver Code Starts
+if __name__ == '__main__':
+    t = int(input())
+    for i in range(t):
+        n = int(input())
+        arr = list(map(int, input().strip().split()))
+        ob = Solution()
+        print(ob.maxLen(n, arr))

Arrays/subarray_sum.py

@@ -0,0 +1,46 @@
+class Solution:
+    def subArraySum(self, arr, n, s):
+        sum_dict = {}
+        pre_sum = 0
+        for id_i in range(n):
+            pre_sum += arr[id_i]
+            if pre_sum > s:
+                k = pre_sum - s
+                idx = sum_dict.get(k)
+                if idx:
+                    return [idx+1, id_i+1]
+            elif pre_sum == s:
+                return [1, id_i+1]
+            sum_dict[pre_sum] = id_i+1
+        return [-1]
+
+
+# {
+# Driver Code Starts
+# Initial Template for Python 3
+
+import math
+
+
+def main():
+    T = int(input())
+    while (T > 0):
+
+        NS = input().strip().split()
+        N = int(NS[0])
+        S = int(NS[1])
+
+        A = list(map(int, input().split()))
+        ob = Solution()
+        ans = ob.subArraySum(A, N, S)
+
+        for i in ans:
+            print(i, end=" ")
+
+        print()
+
+        T -= 1
+
+
+if __name__ == "__main__":
+    main()

Arrays/zigzag_array.py

@@ -0,0 +1,57 @@
+# Problem: convert array into zig-zag fashion
+# https://practice.geeksforgeeks.org/problems/convert-array-into-zig-zag-fashion1638/1
+
+class Solution:
+    # Program for zig-zag conversion of array
+    def zigZag(self, arr, n):
+
+        flag = False
+        i = 0
+        while i < n - 1:
+            if not flag and arr[i] > arr[i + 1]:
+                arr[i], arr[i + 1] = arr[i + 1], arr[i]
+            elif flag and arr[i] < arr[i + 1]:
+                arr[i], arr[i + 1] = arr[i + 1], arr[i]
+
+            flag = not flag
+            i = i + 1
+
+
+# {
+# Driver Code Starts
+# Initial Template for Python 3
+
+import sys
+
+
+def isZigzag(arr, n):
+    f = 1
+
+    for i in range(1, n):
+        if f:
+            if arr[i - 1] > arr[i]:
+                return 0
+        else:
+            if arr[i - 1] < arr[i]:
+                return 0
+        f = f ^ 1
+
+    return 1
+
+
+t = int(input())
+while t:
+    n = int(input())
+    arr = [int(x) for x in input().split()]
+    ob = Solution()
+    ob.zigZag(arr, n)
+    check = isZigzag(arr, n)
+
+    if check:
+        print("1")
+    else:
+        print("0")
+
+    t -= 1
+
+sys.exit(0)