Title description:
Given an integer array and an integer k, you need to find the number of consecutive sub-arrays that sum to k in the array.
Example 1:
Input: nums = [1,1,1], k = 2
Output: 2, [1,1] and [1,1] are two different situations.
Explanation:
The length of the array is [1, 20,000].
The range of the elements in the array is [-1000, 1000], and the range of the integer k is [-1e7, 1e7].
code show as below:
Prefix and:
class Solution {
public int subarraySum(int[] nums, int k) {
int n = nums.length;
int[] arr = new int[n + 1];
arr[0] = 0;
for (int i = 0; i < n; i++) {
arr[i + 1] = arr[i] + nums[i];
}
int ans = 0;
for (int i = 1; i <= n; i++) {
for (int j = 0; j < i; j++) {
if (arr[i] - arr[j] == k) {
ans++;
}
}
}
return ans;
}
}
violence:
class Solution {
public int subarraySum(int[] nums, int k) {
int n = nums.length;
int ans = 0;
for (int i = 0; i < n; i++) {
int sum = 0;
for (int j = i; j < n; j++) {
sum += nums[j];
if (sum == k) {
ans++;
}
}
}
return ans;
}
}
Results of the:
