Pattern problems in C++
Patterns problems in C++ archive here. I will probably keep on updating it as I solve more similar problems.
Problems found from YT videos, websites, or who knows from where. And yea I really did solve them instead of just copying. Pls trust. Pls. No lie me. Me good.
Read it maybe? : These are mostly solved just using for loops. Their are many ways to so solve one pattern, for example some will start i from 1 some from 0, some will use <= to end the loop while some <, some will use some other mathematical formula or view the pattern grid differently, etc. Some problems have more than one method to solve it, showcasing my 900+ IQ. Lol.
Pattern 1 -
* * * *
* * * *
* * * *
* * * *
void print_pattern_01(int n) {
for (int i = 0; i < n; i++) {
for (int j = 0; j < n; j++) {
cout << "* ";
}
cout << endl;
}
}
Pattern 2 -
*
* *
* * *
* * * *
* * * * *
void print_pattern_02(int n) {
for (int i = 0; i < n; i++) {
for (int j = 0; j < i + 1; j++) {
cout << "* ";
}
cout << endl;
}
}
Pattern 3 -
1
1 2
1 2 3
1 2 3 4
1 2 3 4 5
void print_pattern_03(int n) {
for (int i = 0; i < n; i++) {
for (int j = 1; j < i + 1; j++) {
cout << j << " ";
}
cout << endl;
}
}
Pattern 4 -
1
2 2
3 3 3
4 4 4 4
5 5 5 5 5
void print_pattern_04(int n) {
for (int i = 0; i < n; i++) {
for (int j = 1; j < i + 1; j++) {
cout << i + 1 << " ";
}
cout << endl;
}
}
Pattern 5 -
* * * *
* * *
* *
*
void print_pattern_05(int n) {
for (int i = 0; i < n; i++) {
for (int j = 0; j < n - i; j++) {
cout << "* ";
}
cout << endl;
}
}
1 2 3 4 5
1 2 3 4
1 2 3
1 2
1
void print_pattern_06(int n) {
for (int i = 0; i < n; i++) {
for (int j = 1; j < n + 1 - i; j++) {
cout << j << " ";
}
cout << endl;
}
}
Pattern 7 -
*
***
*****
*******
*********
void print_pattern_07(int n) {
for (int i = 0; i < n; i++) {
// Prints first half
// *
// **
// ***
// ****
// *****
for (int j = 0; j < n; j++) {
if (j < n - i - 1)
cout << " ";
else
cout << "*";
}
// Prints second half -
//
// *
// **
// ***
// ****
for (int k = 0; k < i; k++) {
cout << "*";
}
cout << endl;
}
}
void print_pattern_07(int n) {
for (int i = 0; i < n; i++) {
for (int j = 0; j < n - i - 1; j++) {
cout << " ";
}
for (int j = 0; j < 2 * i + 1; j++) {
cout << "*";
}
cout << endl;
}
}
Pattern 8 -
*********
*******
*****
***
*
void print_pattern_08(int n) {
for (int i = 0; i < n; i++) {
// Prints first half -
// *****
// ****
// ***
// **
// *
for (int j = 0; j < n; j++) {
if (j < i)
cout << " ";
else
cout << "*";
}
// Prints second half -
// ****
// ***
// **
// *
//
for (int k = 0; k < n - i - 1; k++) {
cout << "*";
}
cout << endl;
}
}
void print_pattern_08(int n) {
for (int i = 0; i < n; i++) {
for (int j = 0; j < i; j++) {
cout << " ";
}
for (int j = 0; j < 2 * (n - i) - 1; j++) {
cout << "*";
}
cout << endl;
}
}
Pattern 9 -
*
***
*****
*******
*********
*******
*****
***
*
void print_pattern_09(int n)
{
// For n = 5
// Prints first part -
// *
// ***
// *****
// *******
// *********
for (int i = 0; i < n; i++) {
for (int j = 0; j < n - i - 1; j++) {
cout << " ";
}
for (int j = 0; j < 2 * i + 1; j++) {
cout << "*";
}
cout << endl;
}
// Prints second half -
// *******
// *****
// ***
// *
for (int i = 1; i < n; i++) {
for (int j = 0; j < i; j++) {
cout << " ";
}
for (int j = 0; j < 2 * (n - i) - 1; j++) {
cout << "*";
}
cout << endl;
}
}
Pattern 10 -
*
**
***
****
*****
****
***
**
*
void print_pattern_10(int n) {
// Considering n as till the row with maximum stars
// Therefore n = 5
// Prints first half -
// *
// **
// ***
// ****
// *****
for (int i = 0; i < n; i++) {
for (int j = 0; j < i + 1; j++) {
cout << "*";
}
cout << endl;
}
// Prints second half -
// ****
// ***
// **
// *
for (int i = 1; i < n; i++) {
for (int j = 0; j < n - i; j++) {
cout << "*";
}
cout << endl;
}
}
void print_pattern_10(int n) {
// Here we consider n = total number of rows
// Therefore n = 9
for (int i = 0; i < 2 * n - 1; i++) {
int stars = i + 1;
if (i > n - 1) stars = ((2 * n) - (i + 1));
for (int j = 0; j < stars; j++) {
cout << "*";
}
cout << endl;
}
}
Pattern 11 -
1
0 1
1 0 1
0 1 0 1
1 0 1 0 1
void print_pattern_11(int n) {
short flip = 1;
for (int i = 0; i < n; i++) {
if (i % 2 == 0) flip = 1;
else flip = 0;
for (int j = 0; j < i + 1; j++) {
cout << flip << " ";
flip = 1 - flip;
}
cout << endl;
}
}
Pattern 12 -
1 1
12 21
123 321
1234 4321
1234554321
void print_pattern_12(int n) {
for (int i = 0; i < n; i++) {
// first half
for (int j = 0; j < i + 1; j++) {
cout << j + 1;
}
// spaces
for (int j = 0; j < 2 * (n - i - 1); j++) {
cout << " ";
}
// second half
for (int j = i + 1; j > 0; j--) {
cout << j;
}
cout << endl;
}
}
Pattern 13 -
1
2 3
4 5 6
7 8 9 10
11 12 13 14 15
void print_pattern_13(int n) {
int x = 1;
for (int i = 0; i < n; i++) {
for (int j = 0; j < i + 1; j++) {
cout << x++ << " ";
}
cout << endl;
}
}
Pattern 14 -
A
AB
ABC
ABCD
ABCDE
void print_pattern_14(int n) {
for (int i = 0; i < n; i++) {
char x = 'A';
for (int j = 0; j < i + 1; j++) {
cout << x;
x = x + 1;
}
cout << endl;
}
}
void print_pattern_14(int n) {
for (char i = 'A'; i < 'A' + n; i++) {
for (char j = 'A'; j < i + 1; j++) {
cout << j;
}
cout << endl;
}
}
void print_pattern_14(int n) {
for (int i = 0; i < n; i++) {
for (char j = 'A'; j < 'A' + i + 1; j++) {
cout << j;
}
cout << endl;
}
}
Pattern 15 -
ABCDE
ABCD
ABC
AB
A
void print_pattern_15(int n) {
for (int i = 0; i < n; i++) {
char x = 'A';
for (int j = 0; j < n - i; j++) {
cout << x;
x = x + 1;
}
cout << endl;
}
}
void print_pattern_15(int n) {
for (int i = 0; i < n; i++) {
for (char j = 'A'; j < 'A' + (n - i); j++) {
cout << j;
}
cout << endl;
}
}
Pattern 16 -
A
BB
CCC
DDDD
EEEEE
void print_pattern_16(int n) {
char ch = 'A';
for (int i = 0; i < n; i++) {
for (int j = 0; j < i + 1; j++) {
cout << ch;
}
ch++;
cout << endl;
}
}
Pattern 17 -
A
ABA
ABCBA
ABCDCBA
void print_pattern_17(int n) {
for (int i = 0; i < n; i++) {
// space
for (int j = 0; j < (n - i - 1); j++) {
cout << ' ';
}
// chars
char ch = 'A';
for (int j = 0; j < i + 1; j++) {
cout << ch++;
}
ch = ch - 2;
for (int j = 0; j < i; j++) {
cout << ch--;
}
cout << endl;
}
// No need to print the end spaces for each row.
// Save computation yay!
}
void print_pattern_17(int n) {
for (int i = 0; i < n; i++) {
// space
for (int j = 0; j < (n - i - 1); j++) {
cout << ' ';
}
// chars
char ch = 'A';
for (int j = 0; j < 2 * i + 1; j++) {
if (j < i) {
cout << ch++;
} else {
cout << ch--;
}
}
cout << endl;
}
}
Pattern 18 -
E
D E
C D E
B C D E
A B C D E
void print_pattern_18(int n) {
char ch = 'E';
for (int i = 0; i < n; i++) {
char start_char = ch;
for (int j = 0; j < i + 1; j++) {
cout << ch++ << " ";
}
ch = start_char - 1;
cout << endl;
}
}
void print_pattern_18(int n) {
for (int i = 0; i < n; i++) {
for (char ch = 'E' - i; ch < 'E' + 1; ch++) {
cout << ch << " ";
}
cout << endl;
}
}
Pattern 19 -
**********
**** ****
*** ***
** **
* *
* *
** **
*** ***
**** ****
**********
An attempt to explain my approach to solve these problems through this pattern 19
Method 1 approach -
Idea is to first divide entire pattern into two halves A and B -
Then subdivide the halves A and B into its quadrants (I, II, III, IV) -
Take half A and print its two quadrants (I and II) lines simultaneously -
For this just write the code to print pattern in quadrant II, then write the code to print pattern in quadrant I and then put a cout << endl in the end.
Do the same for second half B.
void print_pattern_19(int n) {
// First half
for (int i = 0; i < n; i++) {
/////////////////////
// Second quadrant //
/////////////////////
// stars
for (int j = 0; j < n - i; j++) {
cout << "*";
}
// spaces
for (int j = 0; j < i; j++) {
cout << " ";
}
////////////////////
// First quadrant //
////////////////////
// spaces
for (int j = 0; j < i; j++) {
cout << " ";
}
// stars
for (int j = 0; j < n - i; j++) {
cout << "*";
}
cout << endl;
}
// Second half
for (int i = 0; i < n; i++) {
////////////////////
// Third quadrant //
////////////////////
// stars
for (int j = 0; j < i + 1; j++) {
cout << "*";
}
// spaces
for (int j = 0; j < n - i - 1; j++) {
cout << " ";
}
/////////////////////
// Fourth quadrant //
/////////////////////
// spaces
for (int j = 0; j < n - i - 1; j++) {
cout << " ";
}
// stars
for (int j = 0; j < i + 1; j++) {
cout << "*";
}
cout << endl;
}
}
Method 2 approach -
Divide the pattern into two halves A and B -
See the following pattern and then simply write the code for stars, then spaces and then again stars for both halves (first half shown here)
Another way to visualize (left side is code from method 1 and right side is code from method 2) -
See how j < i condition was written two times in half A which got combined to j < 2 * i. Same for half B.
void print_pattern_19(int n) {
// First half
for (int i = 0; i < n; i++) {
// stars
for (int j = 0; j < n - i; j++) {
cout << "*";
}
// spaces
for (int j = 0; j < 2*i; j++) {
cout << " ";
}
// stars
for (int j = 0; j < n - i; j++) {
cout << "*";
}
cout << endl;
}
// Second half
for (int i = 0; i < n; i++) {
// stars
for (int j = 0; j < i + 1; j++) {
cout << "*";
}
// spaces
for (int j = 0; j < 2 * (n - i - 1); j++) {
cout << " ";
}
// stars
for (int j = 0; j < i + 1; j++) {
cout << "*";
}
cout << endl;
}
}
Pattern 20 -
* *
** **
*** ***
**** ****
**********
**** ****
*** ***
** **
* *
void print_pattern_20(int n) {
// First half
for (int i = 0; i < n; i++) {
for (int j = 0; j < i + 1; j++) {
cout << "*";
}
for (int j = 0; j < 2 * (n - i - 1); j++) {
cout << " ";
}
for (int j = 0; j < i + 1; j++) {
cout << "*";
}
cout << endl;
}
// Second half
// i = 1 so we can skip i = 0 line printing twice
for (int i = 1; i < n; i++) {
for (int j = 0; j < n - i; j++) {
cout << "*";
}
for (int j = 0; j < 2 * i; j++) {
cout << " ";
}
for (int j = 0; j < n - i; j++) {
cout << "*";
}
cout << endl;
}
}
void print_pattern_20(int n) {
int spaces = 2 * n;
int stars = 0;
for (int i = 0; i < 2 * n - 1; i++) {
if (i >= n) {
stars = 2 * n - i - 1;
spaces += 2;
} else {
stars = i + 1;
spaces -= 2;
}
// Stars
for (int j = 0; j < stars; j++) {
cout << "*";
}
// Spaces
for (int j = 0; j < spaces; j++) {
cout << " ";
}
// Stars
for (int j = 0; j < stars; j++) {
cout << "*";
}
cout << endl;
}
}
Pattern 21 -
* * * * *
* *
* *
* *
* * * * *
void print_pattern_21(int n) {
for (int i = 0; i < n; i++) {
// First and last row
if ((i == 0) || (i == n - 1)) {
for (int j = 0; j < n; j++) {
cout << "* ";
}
cout << endl;
} else {
cout << "* ";
for (int j = 0; j < n - 2; j++) {
cout << " ";
}
cout << "*" << endl;
}
}
}
void print_pattern_21(int n) {
for (int i = 0; i < n; i++) {
for (int j = 0; j < n; j++) {
// Fill with stars only if i or j is in boundary
if (i == 0 || i == n - 1 || j == 0 || j == n - 1) {
cout << "* ";
} else {
cout << " ";
}
}
cout << endl;
}
}
Pattern 22 -
5 5 5 5 5 5 5 5 5
5 4 4 4 4 4 4 4 5
5 4 3 3 3 3 3 4 5
5 4 3 2 2 2 3 4 5
5 4 3 2 1 2 3 4 5
5 4 3 2 2 2 3 4 5
5 4 3 3 3 3 3 4 5
5 4 4 4 4 4 4 4 5
5 5 5 5 5 5 5 5 5
void print_pattern_22(int n) {
for (int i = 0; i < 2 * n - 1; i++) {
for (int j = 0; j < 2 * n - 1; j++) {
// Calculate distances
int top_dist = i;
int bottom_dist = (2 * n - 1) - i - 1;
int left_dist = j;
int right_dist = (2 * n - 1) - j - 1;
// For
// n = 2 -> max dist - 0
// n = 3 -> max dist - 1
// n = 4 -> max dist - 2
// n = 5 -> max dist - 3
// n = n -> max dist - (n - 2)
cout << max(max(top_dist, bottom_dist), max(left_dist, right_dist)) - (n - 2) << " ";
}
cout << endl;
}
}
void print_pattern_22(int n) {
for (int i = 0; i < 2 * n - 1; i++) {
for (int j = 0; j < 2 * n - 1; j++) {
int top_dist = i;
int bottom_dist = (2 * n - 1) - i - 1;
int left_dist = j;
int right_dist = (2 * n - 1) - j - 1;
// Before subtracting n
// 0 0 0 0 0 0 0 0 0
// 0 1 1 1 1 1 1 1 0
// 0 1 2 2 2 2 2 1 0
// 0 1 2 3 3 3 2 1 0
// 0 1 2 3 4 3 2 1 0
// 0 1 2 3 3 3 2 1 0
// 0 1 2 2 2 2 2 1 0
// 0 1 1 1 1 1 1 1 0
// 0 0 0 0 0 0 0 0 0
// So if we subtract n from each cell we get the desired pattern
cout << n - min(min(top_dist, bottom_dist), min(left_dist, right_dist))<< " ";
}
cout << endl;
}
}
Pattern 23 -
*
* *
* * *
* * * *
* * * * *
void print_pattern_23(int n) {
for (int i = 0; i < n; i++) {
for (int j = 0; j < n; j++) {
if (j < n - i - 1)
cout << " ";
else
cout << "* ";
}
cout << endl;
}
}