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hdu2058 The sum problem(枚举~~等差数列求和公式)

时间:2015-03-30 18:10:14      阅读:75      评论:0      收藏:0      [点我收藏+]

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The sum problem

Time Limit: 5000/1000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others)
Total Submission(s): 17697    Accepted Submission(s): 5275


Problem Description
Given a sequence 1,2,3,......N, your job is to calculate all the possible sub-sequences that the sum of the sub-sequence is M.
 

 

Input
Input contains multiple test cases. each case contains two integers N, M( 1 <= N, M <= 1000000000).input ends with N = M = 0.
 

 

Output
For each test case, print all the possible sub-sequence that its sum is M.The format is show in the sample below.print a blank line after each test case.
 

 

Sample Input
20 10 50 30 0 0
 

 

Sample Output
[1,4] [10,10] [4,8] [6,9] [9,11] [30,30]
 
 
#include<stdio.h>
#include<string.h>
#include<math.h>
#include<algorithm>
using namespace std;
#define maxn 1000000
__int64 N,M;
int main()
{
    while(scanf("%I64d%I64d",&N,&M)!=EOF&&N&&M)
    {
        for(__int64 k=(int)sqrt(2*M);k>=1;k--)
        {
            __int64 a1=M/k-(k-1)/2;
            if((2*a1+k-1)*k==2*M)
            {
                printf("[%I64d,%I64d]\n",a1,a1+k-1);
            }
        }
        printf("\n");
    }
    return 0;
}
//根据等差数列求和,m=(2*a1+k-1)*k/2,k表示数列的项数,a1表示首项。
//枚举k(1<=k<=sqtrt(m)) 

 

hdu2058 The sum problem(枚举~~等差数列求和公式)

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原文地址:http://www.cnblogs.com/qianyanwanyu--/p/4378373.html

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