Interleaving Positive and Negative Numbers

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 <= 2) return;
        int pp = partition(A);  //positive number starting posisition
        int np = 0; // negatie number starting position
        if (A.length / 2 < pp) {
            np++;
        }
        // put positive numbers into negative numbers
        while (np <= A.length - 1 && pp <= A.length - 1) {
            swap(A, np, pp);  
            np = np + 2;
            pp++;
        } 
   }

   // move negative to left
   private int partition(int[] A) {
       int p = 0;
       for (int i = 0; i < A.length; i++) {
           if (A[i] < 0) {
               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;
   }
}

转载请注明出处： cnblogs.com/beiyeqingteng/