# 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 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
```

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