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  • 《剑指offer》第五十七题II:为s的连续正数序列

    // 面试题57(二):为s的连续正数序列
    // 题目:输入一个正数s,打印出所有和为s的连续正数序列(至少含有两个数)。
    // 例如输入15,由于1+2+3+4+5=4+5+6=7+8=15,所以结果打印出3个连续序列1~5、
    // 4~6和7~8。
    
    #include <cstdio>
    
    void PrintContinuousSequence(int small, int big);
    
    void FindContinuousSequence(int sum)
    {
        if (sum < 3)
            return;
    
        int small = 1;
        int big = 2;
        int middel = (1 + sum) / 2;  //s的中位数, 因为至少包含2个数字
        int curSum = small + big;
    
        while (small < middel)
        {
            if (curSum == sum)
                PrintContinuousSequence(small, big);
    
            while (curSum > sum && small < middel)  //若结果大于s, 则应减少最小数字
            {
                curSum -= small;
                ++small;
    
                if (curSum == sum)
                    PrintContinuousSequence(small, big);
            }
    
            ++big;
            curSum += big;  //若结果小于s, 则应包含更多数字
        }
    }
    
    void PrintContinuousSequence(int small, int big)
    {
        for (int i = small; i <= big; ++i)
            printf("%d ", i);
    
        printf("
    ");
    }
    // ====================测试代码====================
    void Test(const char* testName, int sum)
    {
        if (testName != nullptr)
            printf("%s for %d begins: 
    ", testName, sum);
    
        FindContinuousSequence(sum);
    }
    
    int main(int argc, char* argv[])
    {
        Test("test1", 1);
        Test("test2", 3);
        Test("test3", 4);
        Test("test4", 9);
        Test("test5", 15);
        Test("test6", 100);
    
        return 0;
    }
    测试代码

    分析:妙啊。

    class Solution {
    public:
        vector<vector<int> > FindContinuousSequence(int sum) {
            
            int small = 1;
            int big = 2;
            int middle = (sum + 1) >> 1;
            int curSum = small + big;
            
            vector<vector<int> > result;
            
            while (small < middle)
            {
                if (curSum == sum)
                    vectorPush(result, small, big);
                
                while (curSum > sum && small < middle)
                {
                    curSum -= small;
                    ++small;
                    
                    if (curSum == sum)
                    vectorPush(result, small, big);
                }
                ++big;
                curSum += big;
            }
            return result;
        }
        vector<vector<int> > vectorPush(vector<vector<int> > &result, int small, int big) //注意引用
        {
            vector<int> temp;
            for (int i = small; i <= big; ++i)
                temp.push_back(i);
            
            result.push_back(temp);
            
            return result;
        }
    };
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  • 原文地址:https://www.cnblogs.com/ZSY-blog/p/12661118.html
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