维护前缀数组sums[],我们维护一个记录前缀和的map,map[x]表示前缀和是x距离当前i最近的下标。 那么状态转移方程就是dp[i] = max(dp[i-1], dp[map[sums[i]-target]]+1) class Solution { public:intdp[100005];intsum[100005];map<int,int> m;intmaxNonOverlapping(vector<int>& nums,inttarget) { ...
Solution 2. Prefix Sum with HashMap, O(N) runtime and space 1. Keep a running prefix sum and a hash map that stores the count of each different prefix sum value; Add (0, 1) to the hashmap, representing a sum of 0 for empty interval. 2. for a given prefix sum ps, check if ...
第一种是prefix sum + 双指针。 例如Minimum Size Subarray Sum - LeetCode: Given an array of n positive integers and a positive integers, find the minimal length of a contiguous subarray of which the sum ≥s. If there isn't one, return 0 instead. 用O(N)时间得到一个prefix sum array,可...
2.Smallest Subarray with a given sum(easy) 2.1 问题描述 2.2 解决方法 2.3 代码 3.课后回顾 4.参考链接 sliding window pattern 1.原理描述 滑动窗口模式(sliding window pattern)是用于在给定数组或链表的特定窗口大小上执行所需的操作,比如寻找包含所有 1 的最长子数组。从第一个元素开始滑动窗口并逐个元素...
leetcode 209 长度最小的子数组 minimum-size-subarray-sum【ct】 思路:设置start和end都为数组第0个元素 , sum为数组的第一个元素,如果和>=target,就start++ ,sum-=nums[start] 否则end-- ,sum+=nums[end] 每次循环中去计算minLength,并返回 etc 数组 leetcode 560. Subarray Sum Equals K 动态规划DP...
Explanation: There are no subarrays with sum target. Expected Time Complexity: O(n). Expected Auxiliary Space: O(1). Constraints: 1≤ arr.size() ≤ 106 1≤ target ≤ arr.size() 0≤ arr[i] ≤ 1 用hashmap处理即可,之前LeetCode上面有类似的题目,这次WA了一次,是put(0,0)了,应该put(0...
Given an array nums and a target value k, find the maximum length of a subarray that sums to k. If there isn’t one, return 0 instead. this is a really easy undetstanding problem. and the follow up is do it in O(n) time. ...
A set of practice note, solution, complexity analysis and test bench to leetcode problem set - leetcode/CountSubArrayFixBound.drawio at b58bcceb0ea27d0756ad72fb6a64b3b547fae221 · brianchiang-tw/leetcode
这题跟560. subarray sum equals k几乎一毛一样。 我想到了用map和sum - k 来实现ONE PASS,但是不知道怎么维护一个类似560题里面那个count的值了。正确答案是用Math.max每次对比当前maxLen 和 i - map.get(sum-k)。 思维难度还是有的。 这题leetcode收费了。我贴一个别人的答案。注意这里的put始终是put...
Since the prefix sum array is monotonically increasing, we can use binary search to find the target index. But the corner case really takes a while to deal with. classSolution{publicintminSubArrayLen(ints,int[] nums){intN=nums.length;if(N ==0)return0;for(inti=1; i < N; ++i) nums...