題目
Given an array of n positive integers and a positive integer s, find the minimal length of a contiguous 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.
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).
Credits:
Special thanks to @Freezen for adding this problem and creating all test cases.
答案
public int minSubArrayLen(int s, int[] nums) {
if(nums.length == 0) return 0;
int sub_sum = nums[0];
int left = 0, right = 0, min = Integer.MAX_VALUE;
while(right < nums.length) {
if(sub_sum >= s) {
min = Math.min(min, right - left + 1);
sub_sum -= nums[left];
if(right == left) right++;
left++;
}
else {
right++;
if(right < nums.length)
sub_sum += nums[right];
}
}
return (min == Integer.MAX_VALUE)? 0 : min;
}
