Given an array with positive and negative integers. Re-range it to interleaving with positive and negative integers.
Note: You are not necessary to keep the original order of positive integers or negative integers.
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.
分析：
其实这题思路还是很简单的，先用partition方法把数组分成两队，左边的数是小于0的数，右边的数是大于0的数。
然后，我们需要把正数插入到负数里，但是之前我们要确认正数负数哪个更多。多的要放在第一个位置。
class Solution {
/**
* @param A: An integer array.
* @return: void
* cnblogs.com/beiyeqingteng/
*/
public void rerange(int[] A) {
if (A == null || A.length <= ) return;
int pp = partition(A); //positive number starting posisition
int np = ; // negatie number starting position
if (A.length / < pp) {
np++;
}
// put positive numbers into negative numbers
while (np <= A.length - && pp <= A.length - ) {
swap(A, np, pp);
np = np + ;
pp++;
}
}
// move negative to left
private int partition(int[] A) {
int p = ;
for (int i = ; i < A.length; i++) {
if (A[i] < ) {
swap(A, i, p);
p++;
}
}
return p;
}
private void swap(int[] A, int i, int j) {
int temp = A[i];
A[i] = A[j];
A[j] = temp;
}
}
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