荷兰国旗问题
1、问题描述
2、解决方法
- 当前数cur<number,则++less,cur++
- 当前数cur>number,则cur,–more
- 当前数cur=number,则cur++
3、代码
public class NetherLandsFlag {
public static int[] partition(int[] arr ,int L ,int R ,int number){
int less = L - 1;
int more = R ;
int cur = L;
while (cur < more){
if (arr[cur] < number){
swap(arr,++less,cur++);
}
else if (arr[cur] > number){
swap(arr,cur,--more);
}
else {
cur++;
}
}
return new int[]{
less+1,more-1};
}
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];
}
public static int[] generateArray() {
int[] arr = new int[10];
for (int i = 0; i < arr.length; i++) {
arr[i] = (int) (Math.random() * 5);
}
return arr;
}
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]);
}
}