LintCode Interleaving Positive and Negative Numbers

description：

Given an array with positive and negative integers. Re-range it to interleaving with positive and negative integers.

Notice

You are not necessary to keep the original order of positive integers or negative integers.

Have you met this question in a real interview? Yes

Example

Given [-1, -2, -3, 4, 5, 6], after re-range, it will be [-1, 5, -2, 4, -3, 6] or any other reasonable answer.

同样是使用two pointers的算法进行处理。但是此时的two pointer的方法是使用的同向的双指针进行的

class Solution {
/**
* @param A: An integer array.
* @return: void
*/
public void rerange(int[] A) {
// write your code here
if (A == null || A.length == 0 || A.length == 1) {
return;
}
int pos = 0;
int neg = 0;
for (int i = 0; i < A.length; i++) {
if (A[i] < 0) {
neg++;
} else {
pos++;
}
}
int posind = 1;
int negind = 0;
if (neg < pos) {
posind = 0;
negind = 1;
}
while (posind < A.length && negind < A.length) {
if (A[posind] > 0) {
posind += 2;
}
if (A[negind] < 0) {
negind += 2;
}
if (posind < A.length && negind < A.length) {
swap(A, posind, negind);
}

}
}
private void swap(int[] A, int left, int right) {
int temp = A[left];
A[left] = A[right];
A[right] = temp;
}
}