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# C# Program for Activity Selection Problem | Greedy Algo-1

You are given n activities with their start and finish times. Select the maximum number of activities that can be performed by a single person, assuming that a person can only work on a single activity at a time. Example:

```Example 1 : Consider the following 3 activities sorted
by finish time.
start[]  =  {10, 12, 20};
finish[] =  {20, 25, 30};
A person can perform at most two activities. The
maximum set of activities that can be executed
is {0, 2} [ These are indexes in start[] and
finish[] ]

Example 2 : Consider the following 6 activities
sorted by finish time.
start[]  =  {1, 3, 0, 5, 8, 5};
finish[] =  {2, 4, 6, 7, 9, 9};
A person can perform at most four activities. The
maximum set of activities that can be executed
is {0, 1, 3, 4} [ These are indexes in start[] and
finish[] ]```

## C#

 `// The following implementation assumes` `// that the activities are already sorted` `// according to their finish time` `using` `System;`   `class` `GFG {` `    ``// Prints a maximum set of activities` `    ``// that can be done by a single` `    ``// person, one at a time.` `    ``// n --> Total number of activities` `    ``// s[] --> An array that contains start` `    ``// time of all activities` `    ``// f[] --> An array that contains finish` `    ``// time of all activities` `    ``public` `static` `void` `printMaxActivities(``int``[] s,` `                                          ``int``[] f, ``int` `n)` `    ``{` `        ``int` `i, j;`   `        ``Console.Write(``"Following activities are selected : "``);`   `        ``// The first activity always gets selected` `        ``i = 0;` `        ``Console.Write(i + ``" "``);`   `        ``// Consider rest of the activities` `        ``for` `(j = 1; j < n; j++) {` `            ``// If this activity has start time greater than or` `            ``// equal to the finish time of previously selected` `            ``// activity, then select it` `            ``if` `(s[j] >= f[i]) {` `                ``Console.Write(j + ``" "``);` `                ``i = j;` `            ``}` `        ``}` `    ``}`   `    ``// Driver Code` `    ``public` `static` `void` `Main()` `    ``{` `        ``int``[] s = { 1, 3, 0, 5, 8, 5 };` `        ``int``[] f = { 2, 4, 6, 7, 9, 9 };` `        ``int` `n = s.Length;`   `        ``printMaxActivities(s, f, n);` `    ``}` `}`   `// This code is contributed` `// by ChitraNayal`

Output:

`Following activities are selected : 0 1 3 4`

Please refer complete article on Activity Selection Problem | Greedy Algo-1 for more details!

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