Given an unsorted array of integers, find the length of longest continuous
increasing subsequence.
Example 1:
Input: [1,3,5,4,7] Output: 3 Explanation: The longest continuous increasing subsequence is [1,3,5], its length is 3. Even though [1,3,5,7] is also an increasing subsequence, it's not a continuous one where 5 and 7 are separated by 4.
Example 2:
Input: [2,2,2,2,2] Output: 1 Explanation: The longest continuous increasing subsequence is [2], its length is 1.
Note: Length of the array will not exceed 10,000.
这道题让我们求一个数组的最长连续递增序列,由于有了连续这个条件,跟之前那道Number of Longest Increasing Subsequence比起来,其实难度就降低了很多。我们可以使用一个计数器,如果遇到大的数字,计数器自增1;如果是一个小的数字,则计数器重置为1。我们用一个变量cur来表示前一个数字,初始化为整型最大值,当前遍历到的数字num就和cur比较就行了,每次用cnt来更新结果res,参见代码如下:
解法一:
class Solution { public: int findLengthOfLCIS(vector<int>& nums) { int res = 0, cnt = 0, cur = INT_MAX; for (int num : nums) { if (num > cur) ++cnt; else cnt = 1; res = max(res, cnt); cur = num; } return res; } };
下面这种方法的思路和上面的解法一样,每次都和前面一个数字来比较,注意处理无法取到钱一个数字的情况,参见代码如下:
解法二:
class Solution { public: int findLengthOfLCIS(vector<int>& nums) { int res = 0, cnt = 0, n = nums.size(); for (int i = 0; i < n; ++i) { if (i == 0 || nums[i - 1] < nums[i]) res = max(res, ++cnt); else cnt = 1; } return res; } };
类似题目:
Number of Longest Increasing Subsequence
参考资料:
https://discuss.leetcode.com/topic/102999/java-c-clean-solution