Given an array of integers that is already sorted in ascending order, find two numbers such that they add up to a specific target number.
The function twoSum should return indices of the two numbers such that they add up to the target, where index1 must be less than index2. Please note that your returned answers (both index1 and index2) are not zero-based.
You may assume that each input would have exactly one solution and you may not use the same element twice.
Input: numbers={2, 7, 11, 15}, target=9
Output: index1=1, index2=2
分析
一個已排序數組，尋找兩個數字的和為指定值葱淳。很簡單的二分查找即可實現钙勃，代碼如下宗兼。
/**
* Return an array of size *returnSize.
* Note: The returned array must be malloced, assume caller calls free().
*/
int* twoSum(int* numbers, int numbersSize, int target, int* returnSize) {
int index1=0,index2=numbersSize-1;
while(index1<index2)
{
if(numbers[index1]+numbers[index2]==target)
break;
else if(numbers[index1]+numbers[index2]<target)
{
index1++;
}
else
index2--;
}
int *ans=(int*)malloc(sizeof(int)*2);
ans[0]=index1+1;
ans[1]=index2+1;
*returnSize=2;
return ans;
}
