Implement theNumArrayclass: NumArray(int[] nums)Initializes the object with the integer arraynums. int sumRange(int left, int right)Returns thesumof the elements ofnumsbetween indicesleftandrightinclusive(i.e.nums[left] + nums[left + 1] + ... + nums[right]). Example 1: Input["NumArr...
Can you solve this real interview question? Range Sum Query 2D - Immutable - Given a 2D matrix matrix, handle multiple queries of the following type: * Calculate the sum of the elements of matrix inside the rectangle defined by its upper left corner (r
Leetcode 304. Range Sum Query 2D - Immutable, Terence_F的文章 classNumArray{ vector<int> dp {0}; public: NumArray(vector<int> &nums) { intsum =0; for(intn: nums) { sum += n; dp.push_back(sum); } } intsumRange(inti,intj){ returndp[j +1] - dp[i]; } };...
代码如下: 1classNumArray {2int[] dp;3publicNumArray(int[] nums) {4if( nums ==null|| nums.length == 0 )return;5dp =newint[nums.length];6dp[0]=nums[0];7for(inti = 1 ; i < nums.length ; i ++){8dp[i] = dp[i-1]+nums[i];9}10}1112publicintsumRange(inti,intj) {13r...
There are many calls to sumRange function.分析:题目的意思很简单,给定一个数组,使用sumRange(i,j)函数来计算两个索引之间元素的和。最简单的方法便是根据给的i,j直接求和。不过在note中我们看到会多次调用sumRange这个函数,如果每次调用都重新求这样时间复杂度会很高。现在...
LeetCode: 303. Range Sum Query - Immutable 题目描述 Given an integer array nums, find the sum of the elements between indices i and j (i ≤ j), inclusive. Example: Given nums = [-2, 0, 3, -5, 2, -1] sumRange(0, 2) -> 1 ...
https://leetcode.com/problems/range-sum-query-immutable/题目: Given an integer array nums, find the sum of the elements between indices i and j (i ≤ j), inclusive. Example: Given nums = [-2, 0, 3, -5, 2, -1] sumRange(0, 2) -> 1 ...
另外一种思路,在数组最前面加上一个0。这样一来,就有sumRange(i, j) = sum[j + 1] - sum[i],避免了可能的越界。 Code //Runtime: 169msclass NumArray{public:vector<int>sum;NumArray(vector<int>nums){inttmp=0;sum.push_back(tmp);intnumSize=nums.size();for(inti=0;i<numSize;i++){...
https://leetcode.com/problems/range-sum-query-immutable/description/ 可以直接 二维 DP 来解决。题解巧妙使用了 Range Sum 的特点:sumRange(i -> j) = sumRange(0 -> j) - sumRange(0 -> i-1),从而实现了降维。 classNumArray{privateint[]sumSoFar;publicNumArray(int[]nums){sumSoFar=newint[...
[LeetCode]--303. Range Sum Query - Immutable 简介:Given an integer array nums, find the sum of the elements between indices i and j (i ≤ j), inclusive.Example: Given nums = [-2, 0, 3, -5, 2, -1]sumRange(0, 2) -> 1sumRange(2, 5) -&...