不定期更新leetcode解题java答案。
采用pick one的方式选择题目。
题意为给定数组,获取满足要求的最长子串的长度。要求为前后两个数字差为绝对的正负关系(差为0不满足要求)。
例如,[1,7,4,9,2,5]
is a wiggle sequence because the differences (6,-3,5,-7,3) 。
7-1=6>0, 4-7=-3<0, 9-4=5>0, 2-9=-7<0, 5-2=3>0。
采用贪心算法先获取两相邻数的差,再进行判断是否满足正负关系。试想若两个连续的差均为大于0的数,例如[2,1,3,5,...],则选取的留下数组有[2,1,3,...]和[2,1,5,...]。
显然后者更佳(容易满足题意),由此可得出如下代码:
1 public class Solution { 2 public int wiggleMaxLength(int[] nums) { 3 if(nums.length == 0) 4 return 0; 5 6 int[] differences = new int[nums.length - 1]; 7 8 for(int i = 0; i < differences.length; i++) 9 differences[i] = nums[i + 1] - nums[i]; 10 11 int count = 1; 12 int lastValue = 0; 13 int difference = 0; 14 for(int i = 0; i < differences.length; i++){ 15 difference = differences[i]; //get difference value 16 17 if(lastValue == 0){ 18 if(difference != 0){ 19 lastValue = difference > 0 ? 1 : -1; 20 count++; 21 } 22 }else{ 23 if(difference * lastValue < 0){ 24 lastValue = lastValue > 0 ? -1 : 1; 25 count++; 26 } 27 } 28 } 29 30 return count; 31 } 32 }
时间: 2024-10-27 06:04:34