209. Minimum Size Subarray Sum

Problem Statement

Pattern: Pattern Sliding Window

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Solution

public static int minSubArrayLen(int target, int[] nums) {
	int start = 0, end = 0, min = Integer.MAX_VALUE, currSum = 0;
	
	// sliding window
	while (end < nums.length) {
		// update currSum
		currSum += nums[end];
		
		// if currSum >= target
		while(start<= end && currSum >= target){
			// update min
			min = Math.min(min, end-start+1);
			// update sum, slide start forward
			currSum -= nums[start++];
		}
		end++;
	}
	// if el not found
	if (min == Integer.MAX_VALUE) min = 0;
	return min;
}

Notes

• Sliding window : move end forward and update sum
  • while (sum >= target) update min, slide window forward, update sum