3SumClosest.java

//O(N^2), o(N)
public class Solution {
    public Integer threeSumClosest(int[] num, int target) {
        // Start typing your Java solution below
        // DO NOT write main() function
        Arrays.sort(num);
        int min = Integer.MAX_VALUE;
        int result = 0;
        for(int i = 0; i < num.length; ++i){
            for(int j = i + 1, k = num.length - 1; j < k;){
                int sum = num[i] + num[j] + num[k];
                int sub = sum - target;
                if(sub > 0) 
		    --k;
                else if(sub < 0)    
		    ++j;
                else{
                    return sum;
                }
                sub = Math.abs(sub);
                if(min > sub){ 
                    min = sub;
                    result = sum;
                }   
            }
            while(i < num.length -1 && num[i] == num[i+1])
                ++i;
        }
        return result;
    }
}