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 sumRange(2, 5) -> -1 sumRange(0, 5) -> -3 N
且关系为sums[i+1]=nums[0]+nums[1]+...+nums[i],所以有sums[i+1]-sums[i]=nums[i]8} //为了方便sumRange的处理910}1112intsumRange(inti,intj) {13returnsums[j+1]-sums[
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 sumRange(2, 5) -> -1 sumRange(0, ...
publicclassNumArray {privateint[] sum;publicNumArray(int[] nums) { sum=newint[nums.length + 1];for(inti = 1; i < sum.length; i++) { sum[i]= nums[i - 1] + sum[i - 1] ; } }publicintsumRange(inti,intj) {returnsum[j + 1] -sum[i]; } }//Your NumArray object will ...
先建立一个与数组nums长度相同的新数组psum,表示nums每个位置之前前所有数字的和。psum数组可以通过C++自带的partial_sum函数建立,也可以直接遍历一遍nums数组,并利用状态转移方程psum[i] = psum[i-1] + nums[i]完成统计。如果我们需要获得位置i和j之间的数字和,只需计算psum[j+1] - psum[i]即可...
第二,sumRange函数会被调用很多次(应该是要求注意算法的时间复杂度)。 另外一点要注意的是,给出的代码结构如下: classNumArray{public:NumArray(vector<int>nums){}intsumRange(inti,intj){}};/** * Your NumArray object will be instantiated and called as such: ...
Range Sum Query - Immutable 思路: 动态规划,每次计算和的时候用上一次计算的结果。时间复杂度为O(n)。不用的话时间复杂度为O(n2). Table 方便查询 比如nums长度是n 查询m次 就是O(nm) 但是存一个NumArray[i],表示从0-i的sum和,那么查询sum[i,j]即为sum[0,j] - sum[0,i] ...
303. Range Sum Query - Immutable Given an integer arraynums, handle multiple queries of the following type: Calculate thesumof the elements ofnumsbetween indicesleftandrightinclusivewhereleft <= right. Implement theNumArrayclass: NumArray(int[] nums)Initializes the object with the integer array...
[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) -&...
Range Sum Query 2D - Immutable 2019-12-10 11:35 − Medium Given a 2D matrix matrix, find the sum of the elements inside the rectangle defined by its upper left corner (row1, col1) and lower ri... 程嘿嘿 0 174 python基础-生成器 2019-12-11 17:14 − 1.什么是生成器:...