g0201_0300.s0300_longest_increasing_subsequence.Solution.kt Maven / Gradle / Ivy
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Kotlin-based LeetCode algorithm problem solutions, regularly updated
package g0201_0300.s0300_longest_increasing_subsequence
// #Medium #Top_100_Liked_Questions #Top_Interview_Questions #Array #Dynamic_Programming
// #Binary_Search #Algorithm_II_Day_16_Dynamic_Programming #Binary_Search_II_Day_3
// #Dynamic_Programming_I_Day_18 #Udemy_Dynamic_Programming
// #2022_09_11_Time_318_ms_(82.28%)_Space_39.2_MB_(82.77%)
class Solution {
fun lengthOfLIS(nums: IntArray): Int {
if (nums.isEmpty()) {
return 0
}
val dp = IntArray(nums.size + 1)
// prefill the dp table
for (i in 1 until dp.size) {
dp[i] = Int.MAX_VALUE
}
val left = 1
var right = 1
for (curr in nums) {
var start = left
var end = right
// binary search, find the one that is lower than curr
while (start + 1 < end) {
val mid = start + (end - start) / 2
if (dp[mid] > curr) {
end = mid
} else {
start = mid
}
}
// update our dp table
if (dp[start] > curr) {
dp[start] = curr
} else if (curr > dp[start] && curr < dp[end]) {
dp[end] = curr
} else if (curr > dp[end]) {
dp[++end] = curr
right++
}
}
return right
}
}