[leetCode] Minimum Size Subarray Sum

Given an array of n positive integers and a positive integer s, find the minimal length of a subarray of which the sum ≥ s. If there isn't one, return
0 instead.

For example, given the array 

[2,3,1,2,4,3]

 and 

s
= 7

,

the subarray 

[4,3]

 has the minimal length under the problem constraint.

click to show more practice.

More practice:
If you have figured out the O(n) solution, try coding another solution of which the time complexity is O(n log n).
O(n log n) solution:
public class Solution {
public int minSubArrayLen(int s, int[] nums) {
int[] acc = new int[nums.length + 1];
for (int i = 1; i < acc.length; i++) {
acc[i] = acc[i-1] + nums[i-1];
}

int len = Integer.MAX_VALUE;

for (int i = 0; i < acc.length; i++) {
int index = search(s + acc[i], acc, i+1, acc.length-1);
if (index == acc.length) break;
if (index - i < len) len = index - i;
}

if (len == Integer.MAX_VALUE) len = 0;
return len;
}

private int search(int s, int[] acc, int l, int r) {
while (r >= l) {
int mid = (r+l)/2;
if (acc[mid] >= s)
r = mid - 1;
else
l = mid + 1;
}
return l;
}
}