**Ascending Cards - Google Top Interview Questions**

### Problem Statement :

You are given a list of integers cards, and are looking to order the cards in a way so that they are revealed in ascending order. The cards are revealed in this manner: the top card is removed and revealed and then next card is moved to the back. This is repeated until there's no more cards. Return an ordering of the cards such that they are revealed in ascending order. Constraints n ≤ 100,000 where n is the length of cards Example 1 Input cards = [1, 2, 3, 4, 5] Output [1, 5, 2, 4, 3] Explanation 1 is removed and 5 is moved to the back, resulting in [2, 4, 3, 5]. 2 is removed and 4 is moved to the back, resulting in [3, 5, 4] 3 is removed and 5 is moved to the back, resulting in [4, 5] 4 is removed and 5 is moved to the back, resulting in [5] 5 is removed and there's no more cards.

### Solution :

` ````
Solution in C++ :
int find(int u, vector<int> &root) {
if (root[u] == u) return u;
return root[u] = find(root[u], root);
}
void unite(int u, int v, vector<int> &root) {
u = find(u, root);
v = find(v, root);
root[u] = v;
}
vector<int> solve(vector<int> &cards) {
sort(cards.begin(), cards.end());
int N = cards.size();
vector<int> root(N);
iota(root.begin(), root.end(), 0);
vector<int> ret(N);
int cur = 0;
for (int i = 0; i < N; ++i) {
ret[cur] = cards[i];
unite(cur, (cur + 1) % N, root);
cur = find((cur + 1) % N, root);
cur = find((cur + 1) % N, root);
/* if you want to combine the above 2 lines, replace with:
cur = find((cur = find((cur + 1) % N, root) + 1) % N, root); */
}
return ret;
}
```

` ````
Solution in Java :
import java.util.*;
class Solution {
public int[] solve(int[] cards) {
int n = cards.length;
Arrays.sort(cards);
int[] res = new int[n];
Deque<Integer> dq = new LinkedList<>();
for (int i = 0; i < n; i++) {
dq.addLast(i);
}
int writeIdx = 0;
for (int c : cards) {
res[dq.pollFirst()] = c;
dq.add(dq.pollFirst());
}
return res;
}
}
```

` ````
Solution in Python :
class Solution:
def solve(self, cards):
n = len(cards)
# create another list where we simulate the game
mapping = list(range(n))
mapping = deque(mapping)
res = [0] * n
for card in sorted(cards):
res[mapping[0]] = card
mapping.popleft()
if mapping:
mapping.append(mapping.popleft())
return res
```

## View More Similar Problems

## Fibonacci Numbers Tree

Shashank loves trees and math. He has a rooted tree, T , consisting of N nodes uniquely labeled with integers in the inclusive range [1 , N ]. The node labeled as 1 is the root node of tree , and each node in is associated with some positive integer value (all values are initially ). Let's define Fk as the Kth Fibonacci number. Shashank wants to perform 22 types of operations over his tree, T

View Solution →## Pair Sums

Given an array, we define its value to be the value obtained by following these instructions: Write down all pairs of numbers from this array. Compute the product of each pair. Find the sum of all the products. For example, for a given array, for a given array [7,2 ,-1 ,2 ] Note that ( 7 , 2 ) is listed twice, one for each occurrence of 2. Given an array of integers, find the largest v

View Solution →## Lazy White Falcon

White Falcon just solved the data structure problem below using heavy-light decomposition. Can you help her find a new solution that doesn't require implementing any fancy techniques? There are 2 types of query operations that can be performed on a tree: 1 u x: Assign x as the value of node u. 2 u v: Print the sum of the node values in the unique path from node u to node v. Given a tree wi

View Solution →## Ticket to Ride

Simon received the board game Ticket to Ride as a birthday present. After playing it with his friends, he decides to come up with a strategy for the game. There are n cities on the map and n - 1 road plans. Each road plan consists of the following: Two cities which can be directly connected by a road. The length of the proposed road. The entire road plan is designed in such a way that if o

View Solution →## Heavy Light White Falcon

Our lazy white falcon finally decided to learn heavy-light decomposition. Her teacher gave an assignment for her to practice this new technique. Please help her by solving this problem. You are given a tree with N nodes and each node's value is initially 0. The problem asks you to operate the following two types of queries: "1 u x" assign x to the value of the node . "2 u v" print the maxim

View Solution →## Number Game on a Tree

Andy and Lily love playing games with numbers and trees. Today they have a tree consisting of n nodes and n -1 edges. Each edge i has an integer weight, wi. Before the game starts, Andy chooses an unordered pair of distinct nodes, ( u , v ), and uses all the edge weights present on the unique path from node u to node v to construct a list of numbers. For example, in the diagram below, Andy

View Solution →