LintCode_14.java

class LintCode_14 {
    /**
     * @param nums: The integer array.
     * @param target: Target to find.
     * @return: The first position of target. Position starts from 0.
     */
    public int binarySearch(int[] nums, int target) {
        //write your code here
         if (nums.length == 0 || nums == null){
             return -1;
         }
         
         int start = 0;
         int end = nums.length - 1;
         
         while (start + 1 < end){
             int mid = start + (end - start) / 2;
             if (nums[mid] == target){
                 end = mid;
             }
             else if (nums[mid] < target){
                 start = mid;
             }
             else{
                 end = mid;
             }
         }
         
         if(nums[start] == target){
             return start;
         }
         if(nums[end] == target){
             return end;
         }
         return -1;
    }
}