COJ 1156 Switching bulbs

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/*Accepted 2352 kb 292 ms C++ 1013 B 2012-04-14 21:39:44 */

#include<cstdio>
#include<cstring>
#include<cstdlib>
#define MAXN 100005

int N, M;
typedef struct
{
    int color, val;
}T;

T t[MAXN];

int cmp( const void *_p, const void *_q)
{
    T *p = ( T *)_p;
    T *q = ( T *)_q;
    return p->val - q->val;
}

int main()
{
    while( scanf( "%d%d", &N, &M) == 2)
    {
        int ans = 0, min = 0x3f3f3f3f;
        for( int i = 0; i < N; i ++)
            scanf( "%d", &t[i].color);
        for( int i = 0; i < N; i ++)
        {
            scanf( "%d", &t[i].val);
            if( t[i].color == 1) {
                ans += t[i].val;
                t[i].val = -t[i].val;
            }
            else t[i].val = t[i].val;
            if( abs(t[i].val) < min)  min = abs(t[i].val);
        }
        qsort( t, N, sizeof t[0], cmp);
        int i;
        for( i = N - 1; i >= 0; i --)
        {
            if( t[i].val < 0 || M == 0) break;
            M --;
            ans += t[i].val;
        }
        if( M % 2)  ans += -min;

        printf( "%d\n", ans);
    }
    return 0;
}