g0201_0300.s0300_longest_increasing_subsequence.Solution Maven / Gradle / Ivy
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Java Solution for LeetCode algorithm problems, continually updating
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_07_06_Time_3_ms_(98.63%)_Space_44.3_MB_(60.27%)
public class Solution {
public int lengthOfLIS(int[] nums) {
if (nums == null || nums.length == 0) {
return 0;
}
int[] dp = new int[nums.length + 1];
// prefill the dp table
for (int i = 1; i < dp.length; i++) {
dp[i] = Integer.MAX_VALUE;
}
int left = 1;
int right = 1;
for (int curr : nums) {
int start = left;
int end = right;
// binary search, find the one that is lower than curr
while (start + 1 < end) {
int 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;
}
}