Find minimum length subarray with sum >= target.
Input: target=7, nums=[2,3,1,2,4,3] → Output: 2. Subarray [4,3] has sum >= 7.
Input: target=4, nums=[1,4,4] → Output: 1
Sliding window: expand right, shrink left when sum >= target.
- Sliding window with left and right pointers
- Expand right, add to sum
- When sum >= target: update min length, subtract left element, advance left
- Return min or 0 if not found
public int minSubArrayLen(int target, int[] nums) {
int left = 0, sum = 0, min = Integer.MAX_VALUE;
for (int right = 0; right < nums.length; right++) {
sum += nums[right];
while (sum >= target) {
min = Math.min(min, right - left + 1);
sum -= nums[left++];
}
}
return min == Integer.MAX_VALUE ? 0 : min;
}
- Time Complexity: O(n)
- Space Complexity: O(1)