LeetCode p303 Range Sum Query - Immutable 题解
1.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, 5) -> -3
题意：
输出数组某一段的累加和。
2.解题思路:
累加 做差
3.代码
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public class {
int[] nums;
public (int[] nums) {
for (int i = 1; i < nums.length; i++) {
nums[i] += nums[i - 1];
}
this.nums = nums;
}
public int sumRange(int i, int j) {
if (i == 0)
return nums[j];
return nums[j] - nums[i - 1];
}
}
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4.一些总结：
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