LeetCode-in-Java
673. Number of Longest Increasing Subsequence
Medium
Given an integer array nums, return the number of longest increasing subsequences.
Notice that the sequence has to be strictly increasing.
Example 1:
Input: nums = [1,3,5,4,7]
Output: 2
Explanation: The two longest increasing subsequences are [1, 3, 4, 7] and [1, 3, 5, 7].
Example 2:
Input: nums = [2,2,2,2,2]
Output: 5
Explanation: The length of longest continuous increasing subsequence is 1, and there are 5 subsequences’ length is 1, so output 5.
Constraints:
1 <= nums.length <= 2000-106 <= nums[i] <= 106
Solution
public class Solution {
public int findNumberOfLIS(int[] nums) {
int[] dp = new int[nums.length];
int[] count = new int[nums.length];
dp[0] = 1;
count[0] = 1;
int result = 0;
int max = Integer.MIN_VALUE;
for (int i = 1; i < nums.length; i++) {
dp[i] = 1;
count[i] = 1;
for (int j = i - 1; j >= 0; j--) {
if (nums[j] < nums[i]) {
if (dp[i] < dp[j] + 1) {
dp[i] = dp[j] + 1;
count[i] = count[j];
} else if (dp[i] == dp[j] + 1) {
count[i] += count[j];
}
}
}
}
for (int i = 0; i < nums.length; i++) {
if (max < dp[i]) {
result = count[i];
max = dp[i];
} else if (max == dp[i]) {
result += count[i];
}
}
return result;
}
}