Minimum Size Subarray Sum
Given an array of n positive integers and a positive integer s, find the minimal length of a 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.
Credits:
Special thanks to @Freezen for adding this problem and creating all test cases.
典型的双指针滑动窗口,前指针扩展,后指针收缩。
记录下每一次sum of [begin, end] ≥ s时候的窗口大小即可。
class Solution { public: int minSubArrayLen(int s, vector<int>& nums) { if(nums.empty()) return 0; int ret = INT_MAX; int n = nums.size(); int begin = 0; int end = 0; int cursum = nums[0]; // guaranteed to exist while(end < n) { // expand while(end < n && cursum < s) { end ++; cursum += nums[end]; } if(end == n) // cursum of [begin, n) < s break; // shrink (cursum >= s) while(begin <= end && cursum >= s) { ret = min(ret, end-begin+1); cursum -= nums[begin]; begin ++; } end ++; cursum += nums[end]; } if(ret == INT_MAX) return 0; else return ret; } };
时间: 2024-11-03 21:28:55