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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