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RemoveDuplicatesFromSortedArray.java
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RemoveDuplicatesFromSortedArray.java
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package com.epi;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.HashSet;
import java.util.List;
import java.util.Random;
import java.util.Set;
public class RemoveDuplicatesFromSortedArray {
// @include
// Returns the number of valid entries after deletion.
public static int deleteDuplicates(List<Integer> A) {
if (A.isEmpty()) {
return 0;
}
int writeIndex = 1;
for (int i = 1; i < A.size(); ++i) {
if (!A.get(writeIndex - 1).equals(A.get(i))) {
A.set(writeIndex++, A.get(i));
}
}
return writeIndex;
}
// @exclude
private static void checkAns(List<Integer> A, int n) {
for (int i = 1; i < n; ++i) {
assert(!A.get(i - 1).equals(A.get(i)));
}
}
private static void smallTest() {
assert(6 == deleteDuplicates(Arrays.asList(2, 3, 5, 5, 7, 11, 11, 11, 13)));
}
public static void main(String[] args) {
smallTest();
Random r = new Random();
int n;
if (args.length == 1) {
n = Integer.parseInt(args[0]);
} else {
n = r.nextInt(10000) + 1;
}
for (int times = 0; times < 1000; ++times) {
List<Integer> A = new ArrayList<>();
for (int i = 0; i < n; i++) {
A.add(r.nextInt(2001) - 1000);
}
Collections.sort(A);
Set<Integer> unique = new HashSet<>(A);
int size = deleteDuplicates(A);
assert(size == unique.size());
checkAns(A, size);
}
}
}