leetcode 209. Minimum Size Subarray Sum

Posted 2020-10-01 いいえ敗者

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.

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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).

 

 

好题目，想法有了，就是实现的时候出现了偏差，导致很长时间没有ac，后来还是看的别人的代码

class Solution {
public:
    int minSubArrayLen(int s, vector<int>& nums) {
        int n = nums.size();
        if (n == 0) return 0;
        int l = 0, r = 0;
        int sum = 0;
        int Min = n + 1;
        while (l < n && r < n) {
            while (sum < s && r < n) sum += nums[r++];
            while (sum >= s && l < n) {
                Min = min(Min, r - l);
                sum -= nums[l++];
            }
        }
        if (Min == n + 1)  return 0;
        return Min;
    }
};