Update 0055-jump-game.kt

nick322 · May 23, 2023 · 7fa5229 · 7fa5229
1 parent a35da60
commit 7fa5229
Showing 1 changed file with 31 additions and 1 deletion.
diff --git a/kotlin/0055-jump-game.kt b/kotlin/0055-jump-game.kt
@@ -1,3 +1,6 @@
+/*
+* O(n) greedy
+*/
 class Solution {
  fun canJump(nums: IntArray): Boolean {
  var goal = nums.size - 1
@@ -9,4 +12,31 @@ class Solution {
  }
  return goal == 0
  }
-}
+}
+
+/*
+* O(n^2) DP + memoization
+*/
+class Solution {
+ fun canJump(nums: IntArray): Boolean {
+ val deadEnd = BooleanArray(nums.size)
+
+ fun canJump(i: Int): Boolean {
+ if (i == nums.lastIndex)
+ return true
+ if (nums[i] == 0 || deadEnd[i] == true)
+ return false
+
+ for (jump in 1..nums[i]) {
+ if (i + jump <= nums.lastIndex && canJump(i + jump)) {
+ return true
+ }
+ }
+
+ deadEnd[i] = true
+ return false
+ }
+
+ return canJump(0)
+ }
+}