Switching element positions (positioning calculation method and the auxiliary space method) array
In the algorithm, often encounter two exchange positions in the array elements of problems or issues variable values exchanged two basic types of data
Auxiliary space method
Exchanging two basic data types of variables
int a=1,b=2;
int tmp=a;
a=b;
b=temp;
//此时a=2,b=1
Exchange positions of elements in the array
public static void swap(int[] arr, int i, int j) {
int tmp = arr[i];
arr[i] = arr[j];
arr[j] = tmp;
}
Bit computing method
Bit exclusive-OR operation (^)
Operational rule
Two numbers into binary, and then start from relatively high, if compared with the same 0, 1 was not the same.
. For example: ^ 11 8
8 binary is converted into a binary 1000,11 1011. The high-order comparison is obtained is:. 0011 binary to decimal and then, is Integer.parseInt ( "0011", 2) = 3;
Exchanging two basic data types of variables
int f = 50; //二进制 110010
int g = 60; //二进制 111100
f = f^g; //110010，111100——>001110
g = f^g; //001110,111100——>110010 ——>50
f = f^g; //001110,110010——>111100 ——>60
System.out.println(f+" "+g);//输出结果是：60 50
Exchange positions of elements in the array
public static void swap(int[] arr, int i, int j) {
arr[i] = arr[i] ^ arr[j];
arr[j] = arr[i] ^ arr[j];
arr[i] = arr[i] ^ arr[j];
}
Both methods comparison
Using a bitwise XOR operation (^) auxiliary space saving, reducing spatial complexity
