Question Definition
Given an unsorted array of integers, find the number of longest increasing subsequence. Example 1:
Input: [1,3,5,4,7]
Output: 2
Explanation: The two longest increasing subsequence are [1, 3, 4, 7] and [1, 3, 5, 7].
Example 2:
Input: [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.
**Note: **Length of the given array will be not exceed 2000 and the answer is guaranteed to be fit in 32-bit signed int.
Java Solution
public int findNumberOfLIS(int[] nums) {
int[][] dp = new int[nums.length][2];
int max = 0;
int maxCount = 0;
for(int i = 0; i < nums.length; i++){
int length = 0;
int count = 1;
for(int j = 0; j < i; j++){
if(nums[j] < nums[i]){
if(dp[j][0] > length){
length = dp[j][0];
count = dp[j][1];
} else if(dp[j][0] == length){
count += dp[j][1];
}
}
}
dp[i][0] = length + 1;
dp[i][1] = count;
if(length > max){
max = length;
maxCount = count;
} else if (length == max){
maxCount += count;
}
}
return maxCount;
}
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