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

• Last Updated : 22 Aug, 2019

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
```

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

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