# Search Insert Position

## Question

Given a sorted array and a target value, return the index if the target is found. If not, return the index where it would be if it were inserted in order.

You may assume no duplicates in the array.

Example
[1,3,5,6], 5 → 2
[1,3,5,6], 2 → 1
[1,3,5,6], 7 → 4
[1,3,5,6], 0 → 0


## 題解

### Java

public class Solution {
/**
* param A : an integer sorted array
* param target :  an integer to be inserted
* return : an integer
*/
public int searchInsert(int[] A, int target) {
if (A == null) {
return -1;
}
if (A.length == 0) {
return 0;
}

int start = 0, end = A.length - 1;
int mid;

while (start + 1 < end) {
mid = start + (end - start) / 2;
if (A[mid] == target) {
return mid; // no duplicates, if not end = target;
} else if (A[mid] < target) {
start = mid;
} else {
end = mid;
}
}

if (A[start] >= target) {
return start;
} else if (A[end] >= target) {
return end; // in most cases
} else {
return end + 1; // A[end] < target;
}
}
}


### C++

class Solution {
/**
* param A : an integer sorted array
* param target :  an integer to be inserted
* return : an integer
*/
public:
int searchInsert(vector<int> &A, int target) {
int N = A.size();
if (N == 0) return 0;
if (A[N-1] < target) return N;
int lo = 0, hi = N;
while (lo < hi) {
int mi = lo + (hi - lo)/2;
if (A[mi] < target)
lo = mi + 1;
else
hi = mi;
}
return lo;
}
};