3SumClosest

3SumClosest.java

public int threeSumClosest(int[] num, int target) {
        if( (num==null) || (num.length<3)  ){
            return target;
        }
        Arrays.sort(num);
        int diff= Integer.MAX_VALUE;
        int closest =0;
        for(int i=0;i<num.length;i++){
            int st=i+1;
            int end=num.length-1;
            while( (st<num.length) && (end>0) && (st<end) ){
                int sum=num[i]+num[st]+num[end];
                if(sum==target){
                    closest = sum;
                    diff =0;
                    break;
                }else if(sum<target){
                    
                    if( ((target-sum)<diff) ){
                        diff = target-sum;
                        closest =sum;
                    }
                    st++;
                }else{
                    
                    if( ((sum-target)<diff) ){
                        diff = sum-target;
                        closest =sum;
                    }
                    end--;
                }
            }
            while(  (i+1)<num.length && (num[i]==num[i+1])  ) i++;
        }
        return closest;
    }