[LeetCode] 674. Longest Continuous Increasing Subsequence #674
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Description
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。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。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;
}
};
Github 同步地址：
类似题目：
Number of Longest Increasing Subsequence
参考资料：
https://leetcode.com/problems/longest-continuous-increasing-subsequence/
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