lc303. Range Sum Query - Immutable

转载于 2019-06-20 03:35:08 发布 · 128 阅读

0 ·

CC 4.0 BY-SA版权

原文链接：https://juejin.im/post/5d0afe91f265da1b602908f3

文章标签：

#python

博客围绕Range Sum Query - Immutable问题展开，给定整数数组，求指定索引区间元素之和。思路是用数组dp记录前n位和，通过计算dp[j]-dp[i-1]得到结果，还需注意i为0的情况，代码使用Python3实现。

摘要生成于 C知道，由 DeepSeek-R1 满血版支持，前往体验 >

Range Sum Query - Immutable Easy

462

769

Favorite

Share 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 Note: You may assume that the array does not change. There are many calls to sumRange function.

思路：用数组dp记录前n位的和，sumRange(i,j)即为计算dp[j]-dp[i-1]的值，注意i为0的情况

代码：python3

class NumArray:

    def __init__(self, nums: List[int]):
        self.dp=nums
        for i in range(len(nums)):
            if i==0:
                self.dp[i]=nums[i]
            else:
                self.dp[i]=self.dp[i-1]+nums[i]
    def sumRange(self, i: int, j: int) -> int:
        if i==0:
            return self.dp[j]
        return self.dp[j]-self.dp[i-1]
复制代码

转载于:https://juejin.im/post/5d0afe91f265da1b602908f3