Reverse String (In-Place & Two Pointers)
Language:
Arrays & StringsTime: O(N)Space: O(1) in-place / O(N) copy
Reverse String (In-Place & Two Pointers)
Standard Technical Benchmark Problem: Reverse String (LeetCode 344) & Palindrome Check
Algorithmic Concept & Core Invariant
Reversing an array or string by swapping elements from both ends using two pointers (left and right) moving towards the center, reducing extra memory overhead.
Interactive Trace: Step 1 / 5
[0]
H
▲ Left[1]
E
-[2]
L
-[3]
L
-[4]
O
▲ RightState Watch:left=0right=4text=HELLO
ACTIONInitialize left=0 ('H') and right=4 ('O')
JavaScript Reference ImplementationZero third-party dependencies
// From user repository: Arrays/reversString.JS
function reverse(str) {
if (!str || typeof str !== 'string' || str.length < 2) return str;
const backwards = [];
const totalItems = str.length - 1;
for (let i = totalItems; i >= 0; i--) {
backwards.push(str[i]);
}
return backwards.join('');
}
// In-place Two Pointers implementation
function reverseStringTwoPointers(chars) {
let left = 0, right = chars.length - 1;
while (left < right) {
const temp = chars[left];
chars[left] = chars[right];
chars[right] = temp;
left++;
right--;
}
return chars;
}Real-World Production Infrastructure Usage
DNA sequence reversal, text protocol parsing, packet payload reversal in network drivers, and palindrome checksum validation.