Queries to check if string B exists as substring in string A

<script>

// Javascript implementation of the approach
var mod = 3803;
var d = 26;

var hash_b = 0;
var hash_a = [];
var mul = [];

// Function to return the modular inverse
// using Fermat's little theorem
function mi(x)
{
    var p = mod - 2;
    var s = 1;
    while (p != 1) {
        if (p % 2 == 1)
            s = (s * x) % mod;
        x = (x * x) % mod;
        p = parseInt(p/2);
    }

    return (s * x) % mod;
}

// Function to generate hash
function genHash(a, b)
{
    // To store prefix-sum
    // of rolling hash
    hash_a = Array(a.length).fill(0);

    // Multiplier for different values of i
    mul = Array(a.length).fill(0);

    // Generating hash value for string b
    for (var i = b.length - 1; i >= 0; i--)
        hash_b = (hash_b * d + (b[i].charCodeAt(0) - 97)) % mod;

    // Generating prefix-sum of hash of a
    mul[0] = 1;
    hash_a[0] = (a[0].charCodeAt(0) - 97) % mod;
    for (var i = 1; i < a.length; i++) {
        mul[i] = (mul[i - 1] * d) % mod;
        hash_a[i]
            = (hash_a[i - 1] + mul[i] * (a[i].charCodeAt(0) - 97)) % mod;
    }
}

// Function that returns true if the
// required sub-string in a is equal to b
function checkEqual(i, len_a, len_b)
{
    // To store hash of required
    // sub-string of A
    var x;

    // If i = 0 then
    // requires hash value
    if (i == 0)
        x = hash_a[len_b - 1];

    // Required hash if i != 0
    else {
        x = (hash_a[i + len_b - 1] - hash_a[i - 1]
             + 2 * mod)
            % mod;
        x = (x * mi(mul[i])) % mod;
    }

    // Comparing hash with hash of B
    if (x == hash_b)
        return true;

    return false;
}

// Driver code
var a = "abababababa";
var b = "aba";

// Generating hash
genHash(a.split(''), b.split(''));

// Queries
var queries = [0, 1, 2, 3];
var q = queries.length

// Perform queries
for (var i = 0; i < q; i++) {
    if (checkEqual(queries[i], a.length, b.length))
        document.write("Yes<br>");
    else
    document.write("No<br>");
}

// This code is contributed by rrrtnx.
</script>

<script>

function substringCheck(stra, strb, query)
{
    // Dp Array
    var matrix = Array.from(Array(strb.length), ()=>Array(stra.length));
  
    // String to character array
    var charCrr = stra.split('');
    var charRrr = strb.split('');
    // initialize matrix with 1
    for (var c = 0; c < stra.length; c++) 
    {
        if (charRrr[0] == charCrr[c]) 
        {
            matrix[0][c] = 1;
        }
    }
    // for r from 1 to string length
    for (var r = 1; r < charRrr.length; r++) 
    {
        var ch = charRrr[r];
        // for c from 1 b string length
        for (var c = 1; c < charCrr.length; c++) 
        {
            if (ch == charCrr[c]
                && matrix[r - 1][c - 1] == 1) 
            {
                matrix[r][c] = 1;
            }
        }
    }
    // For every query
    for (var q of query) 
    {
        var matLoc = (q + (strb.length - 1));
        if (matLoc >= stra.length) {
            document.write(false + "<br>");
        }
        else 
        {
            // print true
            if (matrix[strb.length - 1][(matLoc)]
                == 1) 
            {
                document.write(true+ "<br>");
            }
            else 
            {
                // print false
                document.write(false+ "<br>");
            }
        }
    }
}

// Driver Code
var stra = "GeeksForGeeks";
var strb = "Geeks";
var query = [0,5,8];
substringCheck(stra, strb, query);

// This code is contributed by rutvik_56.
</script>