167. Two Sum II - Input Array Is Sorted

/* TWO POINTER O(n) */
class Solution {
    public int[] twoSum(int[] nums, int target) {
        int front=0;
        int back=nums.length-1;
        while(front<back){
            if(nums[front]+nums[back]==target) return new int[] {front+1, back+1};
            else if(nums[front]+nums[back]>target) back--;
            else front++;
        }
        return new int[] {front+1, back+1};
    }
}


/* BINARY SEARCH O(n) */
class Solution {
    public int[] twoSum(int[] nums, int target) {
        for(int i=0;i<nums.length;i++){
            int find = target-nums[i];  //we are going to find this in remaining array using binary search
            int l=i+1;
            int h=nums.length-1;
            while(l<=h){
                int mid=l+(h-l)/2;
                if(find==nums[mid]) return new int[] {i+1, mid+1};
                else if(nums[mid]<find) l=mid+1;
                else h=mid-1; 
            }
        }
        return new int[] {-1, -1};
    }
}