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majority element in an array #559

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Oct 5, 2021
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majority element in an array #559

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71 changes: 71 additions & 0 deletions Program's_Contributed_By_Contributors/Java_Programs/Misc/majority_Element.java
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Original file line number Diff line number Diff line change
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// import java.util.Arrays;
import java.util.HashMap;

public class majority_Element {
public static void main(String[] args) {
int[] nums = { 2, 2, 1, 1, 1, 2, 2 };
int answer = optimal(nums);
System.out.println(answer);
}

// private static int brute(int[] nums) {
// int n = nums.length;
// for (int i = 0; i < n; i++) {
// int count = 0;
// int element = nums[i];
// for (int j = 0; j < n; j++) {
// if (i != j) {
// if (nums[j] == element) {
// count++;
// }
// }
// if (count > n / 2) {
// return element;
// }
// }
// }
// return -1;
// }

// private static int better1(int[] nums) {
// Arrays.sort(nums);
// if (nums.length <= 1)
// return nums[0];
// Arrays.sort(nums);
// int count = 1;
// for (int i = 0; i < nums.length - 1; i++) {
// if (nums[i] == nums[i + 1]) {
// count++;
// } else {
// count = 1;
// }
// if (count > nums.length / 2)
// return nums[i];
// }
// return -1;
// }

// private static int better2(int[] nums) {
// Arrays.sort(nums);
// return nums[nums.length / 2];
// }

private static int optimal(int[] nums) {
if (nums.length <= 1)
return nums[0];
HashMap<Integer, Integer> map = new HashMap<Integer, Integer>();
for (int i = 0; i < nums.length; i++) {
if (map.containsKey(nums[i])) {
int count = map.get(nums[i]) + 1;
if (count > nums.length / 2)
return nums[i];
else
map.put(nums[i], count);

} else
map.put(nums[i], 1);
}
return -1;
}
}