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Java Program for Activity Selection Problem | Greedy Algo-1
• Difficulty Level : Basic
• 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[] ]
```

## 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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