Skip to content

Navigation Menu

Sign in
Appearance settings

Search code, repositories, users, issues, pull requests...

Provide feedback

We read every piece of feedback, and take your input very seriously.

Saved searches

Use saved searches to filter your results more quickly
Sign up
Appearance settings

Commit c0b0737

Browse files
author
kkarpyshev
committed
Merge remote-tracking branch 'origin/master'
2 parents c6fe792 + 8c29d9b commit c0b0737

File tree

3 files changed

+121
-7
lines changed

3 files changed

+121
-7
lines changed

‎src/easy/141. Linked List Cycle .kt‎

Lines changed: 11 additions & 7 deletions
Original file line numberDiff line numberDiff line change
@@ -1,5 +1,8 @@
11
package easy
22

3+
import HashTableTopic
4+
import LinkedListTopic
5+
import TwoPointersTopic
36
import utils.ListNode
47

58
/**
@@ -12,20 +15,21 @@ import utils.ListNode
1215
* Return true if there is a cycle in the linked list. Otherwise, return false.
1316
*/
1417

15-
class Easy141 {
18+
class Easy141 : HashTableTopic, LinkedListTopic, TwoPointersTopic{
1619

1720
fun hasCycle(head: ListNode?): Boolean {
18-
if (head == null) return false
19-
if (head.next == null || head.next!!.next == null) return false
21+
head ?: return false
22+
head.next ?: return false
23+
head.next?.next ?: return false
2024
if (head === head.next) return true
2125
var t1 = head
22-
var t2 = head.next!!.next
26+
var t2 = head.next?.next
2327
while (true) {
2428
when {
2529
t1 === t2 -> return true
26-
t2!!.next != null && t2.next!!.next != null -> {
27-
t1 = t1!!.next
28-
t2 = t2.next!!.next
30+
t2?.next != null && t2.next!!.next != null -> {
31+
t1 = t1?.next
32+
t2 = t2.next?.next
2933
}
3034
else -> return false
3135
}
Lines changed: 62 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,62 @@
1+
package hard
2+
3+
import CombinatoricsTopic
4+
import DynamicProgrammingTopic
5+
import MathTopic
6+
7+
/**
8+
* 1359. Count All Valid Pickup and Delivery Options
9+
* https://leetcode.com/problems/count-all-valid-pickup-and-delivery-options/
10+
*
11+
Given n orders, each order consist in pickup and delivery services.
12+
Count all valid pickup/delivery possible sequences such that delivery(i) is always after of pickup(i).
13+
Since the answer may be too large, return it modulo 10^9 + 7.
14+
15+
BULLSHIT
16+
*/
17+
18+
class Hard1359 : MathTopic, DynamicProgrammingTopic, CombinatoricsTopic {
19+
20+
private val MOD = 1000000007L
21+
private lateinit var memo: Array<LongArray>
22+
23+
private fun totalWays(unpicked: Int, undelivered: Int): Long {
24+
if (unpicked == 0 && undelivered == 0) {
25+
// We have completed all orders.
26+
return 1
27+
}
28+
if (unpicked < 0 || undelivered < 0 || undelivered < unpicked) {
29+
// We can't pick or deliver more than N items
30+
// Number of deliveries can't exceed number of pickups
31+
// as we can only deliver after a pickup.
32+
return 0
33+
}
34+
if (memo[unpicked][undelivered] != 0L) {
35+
// Return cached value, if already present.
36+
return memo[unpicked][undelivered]
37+
}
38+
var ans: Long = 0
39+
40+
// Count all choices of picking up an order.
41+
ans += unpicked * totalWays(unpicked - 1, undelivered)
42+
// Handle integer overflow.
43+
ans %= MOD
44+
45+
// Count all choices of delivering a picked order.
46+
ans += (undelivered - unpicked) * totalWays(unpicked, undelivered - 1)
47+
// Handle integer overflow.
48+
ans %= MOD
49+
return ans.also { memo[unpicked][undelivered] = it }
50+
}
51+
52+
fun countOrders(n: Int): Int {
53+
memo = Array(n + 1) { LongArray(n + 1) }
54+
return totalWays(n, n).toInt()
55+
}
56+
}
57+
58+
fun main() {
59+
println(Hard1359().countOrders(1))
60+
println(Hard1359().countOrders(2))
61+
println(Hard1359().countOrders(3))
62+
}

‎src/medium/799. Champagne Tower .kt‎

Lines changed: 48 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,48 @@
1+
package medium
2+
3+
import DynamicProgrammingTopic
4+
5+
/**
6+
* 799. Champagne Tower
7+
* https://leetcode.com/problems/champagne-tower/
8+
*
9+
We stack glasses in a pyramid, where the first row has 1 glass, the second row has 2 glasses, and so on until the 100th row.
10+
Each glass holds one cup of champagne.
11+
12+
Then, some champagne is poured into the first glass at the top.
13+
When the topmost glass is full, any excess liquid poured will fall equally to the glass immediately to the left and right of it.
14+
When those glasses become full, any excess champagne will fall equally to the left and right of those glasses, and so on.
15+
(A glass at the bottom row has its excess champagne fall on the floor.)
16+
17+
For example, after one cup of champagne is poured, the top most glass is full.
18+
After two cups of champagne are poured, the two glasses on the second row are half full.
19+
After three cups of champagne are poured, those two cups become full - there are 3 full glasses total now.
20+
After four cups of champagne are poured, the third row has the middle glass half full, and the two outside glasses are a quarter full, as pictured below.
21+
22+
Now after pouring some non-negative integer cups of champagne, return how full the jth glass in the ith row is (both i and j are 0-indexed.)
23+
*/
24+
25+
class Medium799 : DynamicProgrammingTopic {
26+
27+
fun champagneTower(poured: Int, query_row: Int, query_glass: Int): Double {
28+
val result = ArrayList<DoubleArray>(query_row + 1)
29+
result.add(doubleArrayOf(poured.toDouble()))
30+
for (i in 1 until query_row + 1) {
31+
val row = DoubleArray(i + 1)
32+
for (j in 0 until result[i - 1].size) {
33+
val score = maxOf(0.0, result[i - 1][j] - 1) / 2
34+
row[j] += score
35+
row[j + 1] += score
36+
}
37+
result.add(i, row)
38+
}
39+
println(result.map { it.toList() })
40+
return minOf(1.0, result[query_row][query_glass])
41+
}
42+
}
43+
44+
fun main() {
45+
println(Medium799().champagneTower(1, 1, 1))
46+
println(Medium799().champagneTower(2, 1, 1))
47+
println(Medium799().champagneTower(100000009, 33, 17))
48+
}

0 commit comments

Comments
(0)

AltStyle によって変換されたページ (->オリジナル) /