Wine trade Wine trading UVA 11054 Gergovia is in Gergovia

A thinking problem, the main method used is the idea transformation.

First, consider the first villages, the first of his own will with | a [1] | labor

1. a [1]> 0 then 2 villages must take a [1] labor to transport, which is required a [1] + a [2] labor
2. a [1] <0 then 2 villages have already -a [1] bottle, you can not buy, that is, a [2] - (- a [1]) = a [1] + a [2 ]

In summary, we have to record the first few villages in the village to bring wine by scanning method, accumulated labor just fine

#include <bits / STDC ++ H.>
 the using  namespace STD;
 int n-;
 int main () {
     the while (~ Scanf ( " % D " , & n-) && n-) {
         Long  Long A, ANS = 0 , Last = 0 ; / / not open LL see ancestors 
        for ( int I = . 1 ; I <= n-; I ++ ) { 
            Scanf ( " % LLD " , & A ); 
            ANS + = ABS (Last); // absolute value because the labor-positive 
            last + a =; // add this time of labor
         }
        printf("%lld\n",ans);
    }
}