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# Java 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[] ]```

## Java

 `// The following implementation assumes that the activities``// are already sorted according to their finish time``import` `java.util.*;``import` `java.lang.*;``import` `java.io.*;` `class` `ActivitySelection {``    ``// 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;` `        ``System.out.print(``"Following activities are selected : n"``);` `        ``// The first activity always gets selected``        ``i = ``0``;``        ``System.out.print(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]) {``                ``System.out.print(j + ``" "``);``                ``i = j;``            ``}``        ``}``    ``}` `    ``// driver program to test above function``    ``public` `static` `void` `main(String[] args)``    ``{``        ``int` `s[] = { ``1``, ``3``, ``0``, ``5``, ``8``, ``5` `};``        ``int` `f[] = { ``2``, ``4``, ``6``, ``7``, ``9``, ``9` `};``        ``int` `n = s.length;` `        ``printMaxActivities(s, f, n);``    ``}``}`

Output:

`Following activities are selected : n0 1 3 4`

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

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