刷题560. Subarray Sum Equals K
一、题目说明
题目560. Subarray Sum Equals K，给一列整数和一个整数k，找到所有子数组和是k的个数。难度是Medium！
二、我的解答
这个题目第一印象是用dp，很快代码就写好了。然而 Memory Limit Exceeded，其中vector
代码如下：
class Solution{
public:
int subarraySum(vector& nums,int k){
int len = nums.size();
int total = 0;
vector > dp(len+1,vector(len+1,0));
for(int i=0;i 三、优化措施
那就一个一计算吧，用dfs:
class Solution{
public:
int subarraySum(vector& nums,int k){
int len = nums.size();
int total = 0;
for(int i=0;i& nums,int start,int k){
int total = 0;
int sum = 0;
for(int i=start;i 性能如下：
Runtime: 464 ms, faster than 24.82% of C++ online submissions for Subarray Sum Equals K.
Memory Usage: 9.8 MB, less than 98.67% of C++ online submissions for Subarray Sum Equals K.