longest increasing subsequence solution

Author: yhkee0404

longest-increasing-subsequence/yhkee0404.dart

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+class Solution {
+  int lengthOfLIS(List<int> nums) {
+    final stack = []; // S(n) = O(n)
+    nums.forEach((x) { // T(n) = O(nlgn)
+                int i = -1, j = stack.length - 1;
+                while (i != j) { // O(lgn)
+                    final int mid = j - ((j - i) >> 1);
+                    if (stack[mid] < x) {
+                        i = mid;
+                    } else {
+                        j = mid - 1;
+                    }
+                }
+                if (++i == stack.length) {
+                    stack.add(x);
+                } else {
+                    stack[i] = x;
+                }
+            });
+    return stack.length;
+  }
+}