Classic Interview 150 Problem P209 Minimum Size Subarray Sum

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2025-11-11

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Problem:

P209 Minimum Size Subarray Sum

https://leetcode.cn/problems/minimum-size-subarray-sum/description/?envType=study-plan-v2&envId=top-interview-150

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#include <vector>
#include <climits>
#include <algorithm>
using std::vector;

class Solution {
public:
    int minSubArrayLen(int target, vector<int>& nums) {
        int n = nums.size();
        int left = 0;
        int curr_sum = 0;
        int res = INT_MAX;

        for (int right = 0; right < n; ++right) {
            curr_sum += nums[right];

            // When the sum within the window is >= target, try to shrink the left boundary.
            while (curr_sum >= target) {
                res = std::min(res, right - left + 1); // Record the minimum length.

                curr_sum -= nums[left];
                left++;
            }
        }

        return (res == INT_MAX ? 0 : res);
    }
};