LeetCode-in-Java/src/main/java/g0001_0100/s0041_first_missing_positive/Solution.java at main · javadev/LeetCode-in-Java · GitHub

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package g0001_0100.s0041_first_missing_positive;

// #Hard #Top_100_Liked_Questions #Top_Interview_Questions #Array #Hash_Table #Udemy_Arrays
// #Big_O_Time_O(n)_Space_O(n) #2024_11_10_Time_1_ms_(100.00%)_Space_57.5_MB_(31.18%)

public class Solution {
    public int firstMissingPositive(int[] nums) {
        for (int i = 0; i < nums.length; i++) {
            while (nums[i] <= nums.length && nums[i] > 0 && nums[nums[i] - 1] != nums[i]) {
                int temp = nums[nums[i] - 1];
                nums[nums[i] - 1] = nums[i];
                nums[i] = temp;
            }
        }
        for (int i = 0; i < nums.length; i++) {
            if (nums[i] != i + 1) {
                return i + 1;
            }
        }
        return nums.length + 1;
    }
}