713. Subarray Product Less Than K——array 题目分析:暴力方法时间超时,所以只能遍历一次... equals 1.修饰方法或属性. public:任何类中都可用. protected:当前包可访问,出了包有特例(继承). 缺省:当前包可访问. private:当前类中的对象this可以调用的 . 2.Object的几个特殊方
这题可以利用HashMap,把出现过的sum 当作key 存入, 把这个sum 出现过的次数 当作value 存入。 遍历nums array,一直更新sum,然后去map 里找有没有 sum - k,有的话说明 sum - k 是一个旧的sum,之前出现过。换句话说,新的sum - 旧的sum = k,说明 新的sum 减去 旧的sum,剩下的那一段的 和 等于k, ...
result+= preSum.get(sum -k); } preSum.put(sum, preSum.getOrDefault(sum,0) + 1); }returnresult; } } https://leetcode.com/problems/subarray-sum-equals-k/discuss/102106/Java-Solution-PreSum-%2B-HashMap The idea behind this approach is as follows: If the cumulative sum(repreesnted by...
Subarray Sum Equals K,是Google、Facebook等公司的高频面试题。本期习题讲解,我们就通过这道题目,介绍非常常用的一个技巧:prefixSum。 先一起来看看题目: 题目描述 Given an array of integers and an integer k, you need to find the total number of contiguous subarrays whose sum equals to k. Example...
Time complexity O(n), Space complexity O (n). Reference: https://leetcode.com/problems/subarray-sum-equals-k/discuss/102106/Java-Solution-PreSum-%2B-HashMap 永远渴望,大智若愚(stay hungry, stay foolish)
public int maxSubArrayLen(int[] nums, int k) { Map<Integer, Integer> map = new HashMap<>(); int max = 0, sum = 0; //this is the crucial step... if the subarray starts from index 0, //we need to count an extra 1 as it is one less than the actual length ...
https://leetcode.com/problems/subarray-sum-equals-k/discuss/102106/Java-Solution-PreSum-%2B-HashMap The idea behind this approach is as follows: If the cumulative sum(repreesnted bysum[i]sum[i] for sum uptoi^{th}ith index) upto two indices is the same, the sum of the elements lying...
[Leetcode] 560. Subarray Sum Equals K Problem: https://leetcode.com/problems/subarray-sum-equals-k/ Solution1: 利用累计和 Time complexity: O(n2) Space complexity: O(n) Solution2: 移动subarray的起点和终点,计算两点之间的和 Time complexity: O(n2) Space complexit......
class Solution { public: int subarraySum(vector<int>& nums, int k) { int n = nums.size(), sum = 0, res = 0; vector<int> pre(n); unordered_map<int, int> mp; mp[0] = 1; for(int i = 0; i < n; ++i) { sum += nums[i]; pre[i] = sum; } for(int i = 0; i...
LeetCode力扣 560. 和为 K 的子数组 Subarray Sum Equals KEdward留学求职 立即播放 打开App,流畅又高清100+个相关视频 更多438 -- 10:52 App 4 新手一天 100 道力扣题挑战|树的最大深度 双序 DFS 460 -- 10:41 App 1 新手一天100道力扣题挑战|树的最大深度 先序BFS 90 -- 7:22 App LeetCode...