Two Pointers
String
Description
Write a function that reverses a string. The input string is given as an array of characters s
.
You must do this by modifying the input array in-place with O(1)
extra memory.
Example 1:
Input: s = ["h","e","l","l","o"]
Output: ["o","l","l","e","h"]
Example 2:
Input: s = ["H","a","n","n","a","h"]
Output: ["h","a","n","n","a","H"]
Constraints:
Solutions
Solution 1
Python3 Java C++ Go TypeScript Rust JavaScript
class Solution :
def reverseString ( self , s : List [ str ]) -> None :
i , j = 0 , len ( s ) - 1
while i < j :
s [ i ], s [ j ] = s [ j ], s [ i ]
i , j = i + 1 , j - 1
class Solution {
public void reverseString ( char [] s ) {
for ( int i = 0 , j = s . length - 1 ; i < j ; ++ i , -- j ) {
char t = s [ i ] ;
s [ i ] = s [ j ] ;
s [ j ] = t ;
}
}
}
class Solution {
public :
void reverseString ( vector < char >& s ) {
for ( int i = 0 , j = s . size () - 1 ; i < j ;) {
swap ( s [ i ++ ], s [ j -- ]);
}
}
};
func reverseString ( s [] byte ) {
for i , j := 0 , len ( s ) - 1 ; i < j ; i , j = i + 1 , j - 1 {
s [ i ], s [ j ] = s [ j ], s [ i ]
}
}
/**
Do not return anything, modify s in-place instead.
*/
function reverseString ( s : string []) : void {
for ( let i = 0 , j = s . length - 1 ; i < j ; ++ i , -- j ) {
[ s [ i ], s [ j ]] = [ s [ j ], s [ i ]];
}
}
impl Solution {
pub fn reverse_string ( s : & mut Vec < char > ) {
let mut i = 0 ;
let mut j = s . len () - 1 ;
while i < j {
s . swap ( i , j );
i += 1 ;
j -= 1 ;
}
}
}
/**
* @param {character[]} s
* @return {void} Do not return anything, modify s in-place instead.
*/
var reverseString = function ( s ) {
for ( let i = 0 , j = s . length - 1 ; i < j ; ++ i , -- j ) {
[ s [ i ], s [ j ]] = [ s [ j ], s [ i ]];
}
};
Solution 2