[{"type":"Paragraph","children":[{"text":"主要思想为降维采用递归方法将k个数之和的问题逐步降维为两数之和再用双指针方法解决两数之和"}],"slateId":"n3GBRzp2LZWK5D4qBA7IC"},{"type":"Paragraph","slateId":"O_zdOfY6RdVftxYlqA4W1","children":[{"text":""}]},{"type":"CodeBlock","activeTabIndex":0,"children":[{"type":"CodeTab","language":"cpp","name":"","children":[{"text":"#include \n#include \nusing namespace std;\n\nclass solution{\npublic:\n vector > forsum(vector & nums, int target){\n sort(nums.begin(),nums.end());//进行排序\n return ksum(nums,(long long)target,0,4);\n }\n \n vector > ksum(vector nums, long long target, int start, int k){\n //nums存储待检索数组 target为目标和 start标记检索起始位置 \n int n=nums.size();\n vector> res;\n \n if(n-starttarget) right--;\n }\n return res;\n }\n \n for(int i=start;i=n-k时 nums所剩元素不足k个\n if(i>0&&nums[i]==nums[i-1]) continue;//nums[i]的去重\n \n if((long long)nums[i]*k>target) break;//剪枝3:当前元素对应最小和过大结束nums的检索\n if((long long)nums[i]+(long long)(k-1)*nums[n-1]