LeetCode-面试题57 - II. 和为s的连续正数序列

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输入一个正整数 target ，输出所有和为 target 的连续正整数序列（至少含有两个数）。

序列内的数字由小到大排列，不同序列按照首个数字从小到大排列。

示例 1：

输入：target = 9
输出：[[2,3,4],[4,5]]
示例 2：

输入：target = 15
输出：[[1,2,3,4,5],[4,5,6],[7,8]]

限制：

1 <= target <= 10^5

滑动窗口:

注意至少两个数，所以序列最左边最大为（target+1）/2，窗口范围和表示为cursum

如果cursum 小于 target , 序列右边加一个数，end++, cursum+=end

如果cursum 大于 target , 序列左边减一个数，cursum-=start，start+1

复制代码

#include <iostream>
#include <vector>
using namespace std;

class Solution {
public:
    vector<vector<int>> findContinuousSequence(int target) {
        if (target < 3) {
            return res;
        }

int start = 1;
        int end = 2;
        int middle = (target + 1) / 2;
        int cursum = start + end;
        while (start<middle) {
            if (cursum == target) {
                getson(start, end);
            }

while (cursum >target && start < middle) {
                cursum -= start;
                start++;
                if (cursum == target) {
                    getson(start, end);
                }
            }

end++;
            cursum += end;
        }
        return res;
    }

void getson(int start, int end) {
        vec.clear();
        for (int i = start; i <= end; i++) {
            vec.push_back(i);
        }
        res.push_back(vec);
    }

private:
    vector<int> vec;
    vector<vector<int>> res;
};

int main() {

Solution* ps = new Solution();
    vector<vector<int>> res = ps->findContinuousSequence(9);

for (int i = 0; i < res.size(); i++) {
        for (int j = 0; j < res[i].size(); j++) {
            cout << res[i][j];
        }
        cout << endl;
    }
    return 0;

}

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#include <iostream>
#include <vector>
using namespace std;


class Solution {
public:
    vector<vector<int>> findContinuousSequence(int target) {
        if (target < 3) {
            return res;
        }

        int start = 1;
        int end = 2;
        int middle = (target + 1) / 2;
        int cursum = start + end;
        while (start<middle) {
            if (cursum == target) {
                getson(start, end);
            }

            while (cursum >target && start < middle) {
                cursum -= start;
                start++;
                if (cursum == target) {
                    getson(start, end);
                }
            }

            end++;
            cursum += end;
        }
        return res;
    }


    void getson(int start, int end) {
        vec.clear();
        for (int i = start; i <= end; i++) {
            vec.push_back(i);
        }
        res.push_back(vec);
    }

private:
    vector<int> vec;
    vector<vector<int>> res;
};


int main() {

    Solution* ps = new Solution();
    vector<vector<int>> res = ps->findContinuousSequence(9);


    for (int i = 0; i < res.size(); i++) {
        for (int j = 0; j < res[i].size(); j++) {
            cout << res[i][j];
        }
        cout << endl;
    }
    return 0;

}