First, the basics of reference
Second, the code
package basic_class_01;
public class Code_08_NetherlandsFlag {
public static int[] partition(int[] arr, int l, int r, int p) {
int less = l - 1;
int more = r + 1;
while (l < more) {
if (arr[l] < p) {
swap(arr, ++less, l++);
} else if (arr[l] > p) {
swap(arr, --more, l);
} else {
l++;
}
}
return new int[] { less + 1, more - 1 };
}
// for test
public static void swap(int[] arr, int i, int j) {
int tmp = arr[i];
arr[i] = arr[j];
arr[j] = tmp;
}
// for test
public static int[] generateArray() {
int[] arr = new int[10];
for (int i = 0; i < arr.length; i++) {
arr[i] = (int) (Math.random() * 3);
}
return arr;
}
// for test
public static void printArray(int[] arr) {
if (arr == null) {
return;
}
for (int i = 0; i < arr.length; i++) {
System.out.print(arr[i] + " ");
}
System.out.println();
}
public static void main(String[] args) {
int[] test = generateArray();
printArray(test);
int[] res = partition(test, 0, test.length - 1, 1);
printArray(test);
System.out.println(res[0]);
System.out.println(res[1]);
}
}
The result is
21,001,201,001
00,000,111,122
last position in 40 of
the last 71 position really is a pointer?