POJ1247-Magnificent Meatballs

 

http://poj.org/problem?id=1247

Magnificent Meatballs

Time Limit: 1000MS		Memory Limit: 10000K
Total Submissions: 6739		Accepted: 4471

Description

Sam and Ella run a catering service. They like to put on a show when serving meatballs to guests seated at round tables. They march out of the kitchen with pots of meatballs and start serving adjacent guests. Ella goes counterclockwise and Sam goes clockwise, until they both plop down their last meatball, at the same time, again at adjacent guests. This impressive routine can only be accomplished if they can divide the table into two sections, each having the same number of meatballs. You are to write a program to assist them. 

At these catering events, each table seats 2 <= N <= 30 guests. Each guest orders at least one and at most nine meatballs. Each place at the table is numbered from 1 to N, with the host at position 1 and the host's spouse at position N. Sam always serves the host first then proceeds to serve guests in increasing order. Ella serves the spouse first, then serves guests in decreasing order. The figures illustrate the first two example input cases. 

Input

Input consists of one or more test cases. Each test case contains the number of guests N followed by meatballs ordered by each guest, from guest 1 to guest N. The end of the input is a line with a single zero. 

Output

For each table, output a single line with the ending positions for Sam and Ella, or the sentence indicating an equal partitioning isn't possible. Use the exact formatting shown below. 

Sample Input

5 9 4 2 8 3
5 3 9 4 2 8
6 1 2 1 2 1 2
6 1 2 1 2 1 1
0

Sample Output

Sam stops at position 2 and Ella stops at position 3.
No equal partitioning.
No equal partitioning.
Sam stops at position 3 and Ella stops at position 4.

 

　　其實剛開始對題目的意思沒有把握準，但是把題目的意思理解了之後就非常的簡單，這道題的意思可以簡單的理解為：圓桌上有N個數字，Sam從1的位置開始往N走，而Ella則從N往1走，問他們哪個相遇的位置能讓兩端的數字的和相等；如果不論在哪個位置都不能相等的話，那就輸出 No equal partitioning.

　　好了，現在就簡單多了吧。

#include "stdio.h"
#include "math.h"
#include "string.h"
#include "stdlib.h"

int main(int argc, char const *argv[])
{
    int data[35], _i, n, sum, s1, s2;

    while(scanf("%d", &n), n){
        sum = 0;
        for(_i=0; _i<n; _i++){
            scanf("%d", &data[_i]);
            sum += data[_i];
        }
        s1 = 0, s2 = sum;
        for(_i=0; _i<n; _i++){
            s1 += data[_i];
            s2 -= data[_i];
            if(s1 == s2){
                break;
            }
        }
        if(_i>=n){
            printf("No equal partitioning.\n");
        }else{
            printf("Sam stops at position %d and Ella stops at position %d.\n", _i+1, _i+2);
        }
    }

    return 0;
}