[645. Set Mismatch] #leetcode

645_0828.java

class Solution {
  	// O(n) O(n)
    public int[] findErrorNums(int[] nums) {
        boolean[] res = new boolean[nums.length];
        
        int dup = -1;
        int miss = -1;
        
        for (int i = 0 ; i < nums.length; i++) {
            if (res[nums[i]-1]) {
                dup = nums[i];
            } else {
                res[nums[i]-1] = true;
            }
        }
        
        for (int i = 0 ; i < res.length; i++ ) {
            if (!res[i]) miss = i+1; 
        }
        
        return new int[] {dup, miss};
    }
}

class Solution1 {
  	// O(n) O(1)
    public int[] findErrorNums(int[] nums) {
        int[] res = new int[2];
        
        for (int i : nums ) {
            if (nums[Math.abs(i) - 1] < 0) {
                res[0] = Math.abs(i);
            } else {
                nums[Math.abs(i) - 1] *= -1;
            }
        }
        
        for (int i = 0 ; i < nums.length; i++ ) {
            if (nums[i] > 0) res[1] = i+1; 
        }
        
        return res;
    }
}