C++ Code to Determine if an Image is B/W or Color

Suppose, we are given an image that contains n pixels. The pixels can be of the following color −

• 'C' (cyan)

• 'M' (magenta)

• 'Y' (yellow)

• 'W' (white)

• 'G' (grey)

• 'B' (black)

The color of the i-th pixel is given in the string 'pixels'. Given the string, we have to find out if the given photograph is colorful or black and white. If it is a color photograph it will contain at least one pixel of color 'C', 'M' and 'Y' and we will print 'Color'; otherwise, it will contain pixels of color 'W', 'G', 'B' only and we will print 'BW'.

So, if the input is like n = 10, pixels = "GBWYM", then the output will be Color.

Steps

To solve this, we will follow these steps −

for initialize i := 0, when i < n, update (increase i by 1), do:
   if pixels[i] is not equal to 'B' and pixels[i] is not equal to 'W' and pixels[i] is not equal to 'G', then:
      print("Color")
      return
print("BW")

Example

Let us see the following implementation to get better understanding −

#include <bits/stdc++.h>
using namespace std;
#define N 100
void solve(int n, string pixels ) {
   for (int i = 0 ; i < n; i++) {
      if(pixels[i]!='B' && pixels[i]!='W' && pixels[i]!='G') {
         cout<<"Color";
         return;
      }
   }
   cout<<"BW";
}
int main() {
   int n = 10;
   string pixels = "GBWYM";
   solve(n, pixels);
   return 0;
}

Input

10, "GBWYM"

Output

Color