Check whether an Array is Subarray of another Array

Given two arrays A[] and B[] consisting of and integers. The task is to check whether the array B[] is a subarray of the array A[] or not.

Examples:

Input : A[] = {2, 3, 0, 5, 1, 1, 2}, B[] = {3, 0, 5, 1}
Output : Yes

Input : A[] = {1, 2, 3, 4, 5}, B[] = {2, 5, 6}
Output : No

Recommended: Please try your approach on {IDE} first, before moving on to the solution.

Source : Visa Interview Experience

Simple Approach: A simple approach is to run two nested loops and generate all subarrays of the array A[] and use one more loop to check if any of the subarray of A[] is equal to the array B[].

Efficient Approach : An efficient approach is to use two pointers to traverse both the array simultaneously. Keep the pointer of array B[] still and if any element of A[] matches with the first element of B[] then increase the pointer of both the array else increase the pointer of A and reset the pointer of B to 0. If all the elements of B are matched then print YES otherwise print NO.

Below is the implementation of the above approach:

C++

 // C++ program to check if an array is // subarray of another array    #include using namespace std;    // Function to check if an array is // subarray of another array bool isSubArray(int A[], int B[], int n, int m) {     // Two pointers to traverse the arrays     int i = 0, j = 0;        // Traverse both arrays simultaneously     while (i < n && j < m) {            // If element matches         // increment both pointers         if (A[i] == B[j]) {                i++;             j++;                // If array B is completely             // traversed             if (j == m)                 return true;         }         // If not,         // increment i and reset j         else {             i++;             j = 0;         }     }        return false; }    // Driver Code int main() {     int n = 7, m = 4;        int A[] = { 2, 3, 0, 5, 1, 1, 2 };     int B[] = { 3, 0, 5, 1 };        if (isSubArray(A, B, n, m))         cout << "YES\n";     else         cout << "NO\n";        return 0; }

Java

 // Java program to check if an array is // subarray of another array    import java.io.*;    class GFG {        // Function to check if an array is     // subarray of another array     static boolean isSubArray(int A[], int B[], int n, int m)     {         // Two pointers to traverse the arrays         int i = 0, j = 0;            // Traverse both arrays simultaneously         while (i < n && j < m) {                // If element matches             // increment both pointers             if (A[i] == B[j]) {                 i++;                 j++;                    // If array B is completely                 // traversed                 if (j == m)                     return true;             }             // If not,             // increment i and reset j             else {                 i++;                 j = 0;             }         }            return false;     }        // Driver Code        public static void main(String[] args)     {         int n = 7;         int m = 4;            int A[] = { 2, 3, 0, 5, 1, 1, 2 };         int B[] = { 3, 0, 5, 1 };            if (isSubArray(A, B, n, m))             System.out.println("YES\n");         else             System.out.println("NO\n");     } } // This code is contributed by shs

Python3

 # Python 3 program to check if an array  # is subarray of another array    # Function to check if an array is # subarray of another array def isSubArray(A, B, n, m):            # Two pointers to traverse the arrays     i = 0     j = 0        # Traverse both arrays simultaneously     while (i < n and j < m):                    # If element matches increment          # both pointers         if (A[i] == B[j]):             i += 1             j += 1                # If array B is completely             # traversed             if (j == m):                 return True                # If not, increment i and reset j         else:             i += 1             j = 0        return False    # Driver Code if __name__ == '__main__':     n = 7     m = 4        A = [2, 3, 0, 5, 1, 1, 2]     B = [3, 0, 5, 1]        if (isSubArray(A, B, n, m)):         print("YES")     else:         print("NO")    # This code is contributed by # Sanjit_Prasad

C#

 // C# program to check if an array is // subarray of another array    using System;    class GFG {        // Function to check if an array is     // subarray of another array     static bool isSubArray(int[] A, int[] B, int n, int m)     {         // Two pointers to traverse the arrays         int i = 0, j = 0;            // Traverse both arrays simultaneously         while (i < n && j < m) {                // If element matches             // increment both pointers             if (A[i] == B[j]) {                 i++;                 j++;                    // If array B is completely                 // traversed                 if (j == m)                     return true;             }             // If not,             // increment i and reset j             else {                 i++;                 j = 0;             }         }            return false;     }        // Driver Code     static void Main()     {         int n = 7;         int m = 4;            int[] A = { 2, 3, 0, 5, 1, 1, 2 };         int[] B = { 3, 0, 5, 1 };            if (isSubArray(A, B, n, m))             Console.WriteLine("YES");         else             Console.WriteLine("NO");     }     // This code is contributed by Ryuga }

PHP



Output:

YES

Time Complexity: O(N)
Auxiliary Space: O(1)

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