Remove duplicates from a given string using Hashing
Iterating through the given string and use a map to efficiently track of encountered characters. If a character is encountered for the first time, it’s added to the result string, Otherwise, it’s skipped. This ensures the output string contains only unique characters in the same order as the input string.
Below is the implementation of above approach:
<script>
// javascript program to create a unique String using unordered_map
/* access time in unordered_map on is O(1) generally if no collisions occur
and therefore it helps us check if an element exists in a String in O(1)
time complexity with constant space. */
function removeDuplicates( s , n) {
var exists = new Map();
var st = "";
for (var i = 0; i < n; i++) {
if (!exists.has(s[i])) {
st += s[i];
exists.set(s[i], 1);
}
}
return st;
}
// driver code
var s = "w3wiki";
var n = s.length;
document.write(removeDuplicates(s, n));
</script>
Output:
geksfor
Time Complexity: O(n)
Auxiliary Space: O(n)
Javascript Program To Remove Duplicates From A Given String
Write a javascript program for a given string S which may contain lowercase and uppercase characters. The task is to remove all duplicate characters from the string and find the resultant string.
Note: The order of remaining characters in the output should be the same as in the original string.
Example:
Input: Str = w3wiki
Output: geksfor
Explanation: After removing duplicate characters such as e, k, g, s, we have string as “geksfor”.
Input: Str = HappyNewYear
Output: HapyNewYr
Explanation: After removing duplicate characters such as p, e, a, we have string as “HapyNewYr”.
Naive Approach:
Iterate through the string and for each character check if that particular character has occurred before it in the string. If not, add the character to the result, otherwise the character is not added to result.
Below is the implementation of above approach:
<script>
// JavaScript program to remove duplicate character
// from character array and print in sorted
// order
function removeDuplicate(str, n)
{
// Used as index in the modified string
var index = 0;
// Traverse through all characters
for (var i = 0; i < n; i++)
{
// Check if str[i] is present before it
var j;
for (j = 0; j < i; j++)
{
if (str[i] == str[j])
{
break;
}
}
// If not present, then add it to
// result.
if (j == i)
{
str[index++] = str[i];
}
}
return str.join("").slice(str, index);
}
// Driver code
var str = "w3wiki".split("");
var n = str.length;
document.write(removeDuplicate(str, n));
// This code is contributed by shivanisinghss2110
</script>
Output:
geksfor
Time Complexity : O(n * n)
Auxiliary Space : O(1) , Keeps order of elements the same as input.