/* CPP program to find an order of alphabets
so that given set of words are considered
sorted */
#include <bits/stdc++.h>
using namespace std;
#define MAX_CHAR1 26
void findOrder1(vector<string> v1)
{
int n1 = v1.size();
/* So if n is 1, then any order works */
if (n1 == 1) {
cout << "abcdefghijklmnopqrstuvwxyz";
return;
}
/* Indicates adjacency list of 26 characters*/
vector<int> adj1[MAX_CHAR1];
/* Indicates array tracking the number of edges that are
inward to each node*/
vector<int> in(MAX_CHAR1, 0);
// Traversing through all words in given array
string prev1 = v1[0];
/* Shows (n-1) loops because we already acquired the
first word in the list*/
for (int i = 1; i < n1; ++i) {
string s1 = v1[i];
/* Used to find first such letter in the present string
that is different
from the letter in the previous string at the same index*/
int j;
for (j = 0; j < min(prev1.length(), s1.length()); ++j)
if (s1[j] != prev1[j])
break;
if (j < min(prev1.length(), s1.length())) {
/* In this case, the letter in the previous string
precedes the one in the present string, hence add the letter in the
present string as the child of the letter in the previous string*/
adj1[prev1[j] - 'a'].push_back(s1[j] - 'a');
/* In this case, the number of inward pointing edges to
the node representing the letter in the present string increases
by one*/
in[s1[j] - 'a']++;
/* Used to assign present string to previous string for
the next iteration. */
prev1 = s1;
continue;
}
/* It has been seen that if there exists no such letter
then the string length of the previous string must be less than or
equal to the present string, otherwise no such order exists*/
if (prev1.length() > s1.length()) {
cout << "Impossible";
return;
}
/* Used to assign present string to previous string for the
next
iteration */
prev1 = s1;
}
/* Here, topological ordering requires the source nodes
that have no parent nodes*/
stack<int> stk1;
for (int i = 0; i < MAX_CHAR1; ++i)
if (in[i] == 0)
stk1.push(i);
/* Shows vector storing required order (anyone that satisfies)
*/
vector<char> out1;
/* Shows array to keep track of visited nodes */
bool vis1[26];
memset(vis1, false, sizeof(vis1));
/* Indicates standard DFS */
while (!stk1.empty()) {
/* Used to acquire present character */
char x1 = stk1.top();
stk1.pop();
/* Used to mark as visited */
vis1[x1] = true;
/* Usedto insert character to output vector */
out1.push_back(x1 + 'a');
for (int i = 0; i < adj1[x1].size(); ++i) {
if (vis1[adj1[x1][i]])
continue;
/* Because we have already included the present
character in the order, the number edges inward
to this child node can be reduced*/
in[adj1[x1][i]]--;
if (in[adj1[x1][i]] == 0)
stk1.push(adj1[x1][i]);
}
}
/* Verify if all nodes(alphabets) have been visited.
Order is impossible if any one is unvisited*/
for (int i = 0; i < MAX_CHAR1; ++i)
if (!vis1[i]) {
cout << "Impossible";
return;
}
for (int i = 0; i < out1.size(); ++i)
cout << out1[i];
}
// Driver code
int main()
{
vector<string> v1{ "efgh", "wxyz" };
findOrder1(v1);
return 0;
}
About Online C++ Compiler
Try our Online C++ Compiler (Version GNU GCC v11.3.0) to Edit, Run, and Share your C++ Code directly from your browser. This online development environment provides you the latest version GNU GCC v11.3.0.
How to use Online C++ Compiler?
Write and Execute Code
- Write your program (or, paste it) directly under the "Source Code" tab.
- If you want to save your program, go to the "Project" menu and save it.
- You can directly execute your program without saving it by clicking on on "Execute" button.
User Input
The latest version of Coding Ground allows to provide program input at run time from the termnial window exactly the same way as you run your program at your own computer. So simply run a program and provide your program input (if any) from the terminal window available in the right side.
Online C++ Compiler: Keyboard Shortcuts
The following are the keyword shortcut of this Online C++ Compiler:
Shortcut | Description |
⌘ + Enter | Run the program |
⌘ + S | Save Project (Login Required) |
⇧ + ⌘ + S | Save As Project |
⌘ + P | New Project |
⌘ + G | Share Project |
⌘ + Z | Undo Editing |
⌘ + Y | Redo Editing |
⌘ + A | Select All Text |
⌘ + X | Cut Selected Text |
⌘ + C | Copy Selected Text |
⌘ + V | Paste Copied Text |
⌘ + F | Search Text |
⌘ + ⌥ + F | Replace Text |
Shortcut | Description |
Ctrl + Enter | Run the program |
Ctrl + S | Save Project |
Shift + Ctrl + S | Save As Project |
Ctrl + G | Share Project |
Ctrl + Z | Undo Editing |
Ctrl + Y | Redo Editing |
Ctrl + A | Select All Text |
Ctrl + X | Cut Selected Text |
Ctrl + C | Copy Selected Text |
Ctrl + V | Paste Copied Text |
Ctrl + F | Search Text |
Ctrl + H | Replace Text |
Online C++ Compiler: Save and Share C++ Code (Project)
Save C++ Project Online
You can save your C++ Project with us so that you can access this project later on. To save a project you will need to create a login Id with us. So before you save a project, please create a login Id using a link given at the top right corner of this page.
Share C++ Project Online
You can use this feature to share your C++ Code with your teachers, classmates and colleagues. Just click Share Button and it will create a short link, which can be shared through Email, WhatsApp or even through Social Media. A shared link will be deleted if it has been passive for almost 3 months.
More Features of Online C++ Compiler
- Theme – You can change the current editor's theme from the "Editor Theme" option under "Settings" menu.
- Font Size – You can change the font size of the editor /compiler from from the "Font Size" option under "Settings" menu.
- Tab Size – You can change the tab size from the "Tab Size" option under "Settings" Menu.
- Show/Hide Line Numbers – You can show/hide the line number with the code from the "Show Line Numbers" or "Hide Line Numbers" option under "Settings" Menu.
- And, many more.
Benefits of Using Online C++ Compiler
There are several benefits of using the Online C++ Compiler to run your C++ code:
- Platform independence: You can run your code from any device without taking care of operating systems.
- Convenience: You don't need to install anything for using this.
- No setup required: There is no need for additional setup to run your code.
- Updated version: Our online compiler/editors/terminals are the latest up-to-date.