leetcode MaximumGap
z
 2019-04-09 10:36:27   
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public class MaximumGap {
  /**
   * Given an unsorted array, find the maximum difference between the successive elements in its sorted form.
   *
   * Return 0 if the array contains less than 2 elements.
   *
   * Example 1:
   *
   * Input: [3,6,9,1]
   * Output: 3
   * Explanation: The sorted form of the array is [1,3,6,9], either
   *              (3,6) or (6,9) has the maximum difference 3.
   * Example 2:
   *
   * Input: [10]
   * Output: 0
   * Explanation: The array contains less than 2 elements, therefore return 0.
   * Note:
   *
   * You may assume all elements in the array are non-negative integers and fit in the 32-bit signed integer range.
   * Try to solve it in linear time/space.
   */
  public static int solution(int[] nums){
    if (nums.length <2){
      return 0;
    }
    int base = 10;
    int r = 1;
    int maxNumber = nums[0];
    // find the max number.
    for (int i=1; i<nums.length; i++){
      maxNumber = Math.max(maxNumber, nums[i]);

    }

    int[] sorted = new int[nums.length];

    while(maxNumber/r > 0){
      int[] count = new int[base];

      for (int i=0; i<nums.length; i++){
        count[(nums[i]/r) % 10] += 1;
      }

      for (int i=1; i<count.length; i++){
        count[i] += count[i-1];
      }

      for (int i=nums.length-1; i>=0; i--){
        sorted[--count[(nums[i]/r) % 10]] = nums[i];
      }


      for (int i=0; i<nums.length; i++){
        nums[i] = sorted[i];
      }
      r *= 10;
    }
    maxNumber = 0;
    // find the max number.
    for (int i=1; i<nums.length; i++){
      maxNumber = Math.max(maxNumber, nums[i]-nums[i-1]);
    }
    return maxNumber;

  }
  public static void main(String args[]){
    int[] test = new int[]{4,3,9,0};
    System.out.println(solution(test));
  }
}