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Added New Java file in Java/Misc #2005

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Added New Java file in Java/Misc
AzadN Nov 4, 2020
ee34da4
Update largestRange.java
AzadN Nov 4, 2020
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Update largestRange.java
AzadN Nov 4, 2020
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Update largestRange.java
AzadN Nov 4, 2020
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Update largestRange.java
AzadN Nov 4, 2020
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Update largestRange.java
AzadN Nov 6, 2020
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46 changes: 46 additions & 0 deletions Misc/largestRange.java
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import java.util.*;

public class largestRange {

// Finds the length of longest occurring consecutive numbers range in an array
public static int longestRange(int[] nums) {
int longestRange = 0;
HashMap<Integer, Boolean> num = new HashMap<>();

/**
* Stores a mapping of a number to whether the current number is part of a particular
* consecutive range or not.
*/
for (int x : nums) num.put(x, true);
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@prashantdoshi28 prashantdoshi28 Nov 12, 2020 •
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I'm not sure but can't we just use lookahead type of approach over here?

For example,

int[] input_arr = new int[]{0,1,2,4,5,6,0,1};
int count = 1;
int temp_count = 1;
for (int i = 1; i < input_arr.length; i++) {
    if (input_arr[i] != input_arr[i - 1] + 1) {
        if (temp_count > count) {
            count = temp_count;
        }
        temp_count = 1;
    } else temp_count++;
}
System.out.println(count); // Prints 3

If I have misunderstood requirements or this does not work as intended (I haven't tested it, so it is be possible), please let me know.

If above works just as fine, please can you explain this approach's necessity?

This is just a suggestion, not a requirement.

Please do needful and let me know.

for (int x : nums) {
if (!num.get(x)) continue;
num.replace(x, false);
int currentRange = 1;
int left = x - 1;
int right = x + 1;
while (num.containsKey(left)) { // Search leftwards for consecutive range
num.replace(left, false);
currentRange += 1;
left--;
}
while (num.containsKey(right)) { // Search rightwards for consecutive range
num.replace(right, false);
currentRange += 1;
right++;
}
if (currentRange > longestRange)
longestRange = currentRange; // Store longest range at every interation
}
return longestRange;
}

public static void main(String[] args) {
// Testcases
assert longestRange(new int[] {1, 2, 3, 4, -1, 11, 10}) == 4;
// The longest consecutive number range is of length 4 i.e. {1, 2, 3, 4}
assert longestRange(new int[] {-1, 1, 3, 5, 7}) == 1;
// The longest consecutive number range is of length 1 i.e. any of the elements alone
assert longestRange(new int[] {0, 1, 2, 3, 4, 7, 6, 5}) == 8;
// The longest consecutive number range is of length 8 i.e. {0, 1, 2, 3, 4, 5, 6, 7}
}
}