?? 1956.cpp
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/* This Code is Submitted by wywcgs for Problem 1956 on 2005-11-06 at 19:25:15 */
#include <cstdio>
#include <cstring>
#include <algorithm>
using namespace std;
const int MAX = 32;
int stick[MAX], a[MAX];
int n;
bool used[MAX];
bool combin(int, int, int, int);
int main()
{
int T, t, i;
int sum;
scanf("%d", &T);
for(t = 0; t < T; t++) {
scanf("%d", &n);
sum = 0;
for(i = 0; i < n; i++) {
scanf("%d", &stick[i]);
sum += stick[i];
}
a[0] = stick[0];
for(i = 1; i < n; i++) {
a[i] = a[i-1] + stick[i];
}
memset(used, false, sizeof(used));
if(sum % 4 != 0) {
printf("no\n");
} else {
sort(stick, stick+n);
sum /= 4;
if(combin(0, sum, n, 4*sum)) {
printf("yes\n");
} else {
printf("no\n");
}
}
}
return 0;
}
bool combin(int cur, int l, int next, int sum)
{
int i;
if(sum == 0) {
return true;
} else {
for(i = next-1; i >= 0; i--) {
if(cur + a[i] < l) {
return false;
} else {
if(!used[i] && cur + stick[i] <= l) {
used[i] = true;
int p;
if(cur + stick[i] == l) {
p = n;
} else {
p = i;
}
if(combin((cur+stick[i])%l, l, p, sum-stick[i])) {
return true;
}
used[i] = false;
if(cur == 0) {
return false;
}
}
}
}
}
return false;
}
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