/*class NumArray { public: NumArray(vector<int> nums) { myNums.swap(nums); } int sumRange(int i, int j) { int sum = 0; for(int q = i; q <= j; ++q){ sum += myNums[q]; } return sum; } private: vector<int> myNums; };*/ class NumArray { public: NumArray(vector...
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...
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
You may assume that the array does not change. There are many calls to sumRange function. 解题思路 —— 前缀和 记录下前缀和, 即,PrefixSum[i] 表示前 i 个数字的和。 特别地,当 i = 0 时, PrefixSum[i] = 0。 则...
packageleetcodeimport("/halfrost/LeetCode-Go/template")//解法一 线段树,sumRange 时间复杂度 O(1)// NumArray definetypeNumArraystruct{st*template.SegmentTree}// Constructor303 definefuncConstructor303(nums[]int)NumArray{st:=template.SegmentTree{}st.Init(nums,func(i,jint)int{returni+j})returnNu...
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) -&...
Golang中如何实现Range Sum Query - Immutable功能? 在Leetcode 303题中,Golang的解法有哪些优化技巧? Golang实现Range Sum Query - Immutable时,时间复杂度是多少? 版权声明:原创勿转 https://cloud.tencent.com/developer/article/1412946 思路 保存一个slice code 代码语言:javascript 代码运行次数:0 运行 AI...
LeetCode-3/C++/range-sum-query-2d-immutable.cpp Go to file 41 lines (35 sloc) 1.08 KB Raw Blame // Time: ctor: O(m * n), // lookup: O(1) // Space: O(m * n) class NumMatrix { public: NumMatrix(vector<vector<int>> &matrix) { if (matrix.empty()) { return; } const...