uva1354 枚举二叉树

// UVa1354 Mobile Computing
// Rujia Liu
#include<cstdio>
#include<cstring>
#include<vector>
using namespace std;

struct Tree {
double L, R; // distance from the root to the leftmost/rightmost point
Tree():L(0),R(0) {}
};

const int maxn = 6;

int n, vis[1<<maxn];
double r, w[maxn], sum[1<<maxn];
vector<Tree> tree[1<<maxn];

void dfs(int subset) {
if(vis[subset]) return;
vis[subset] = true;

bool have_children = false;
for(int left = (subset-1)⊂ left; left = (left-1)&subset) {
have_children = true;

int right = subset^left;  //补集
double d1 = sum[right] / sum[subset];
double d2 = sum[left] / sum[subset];

dfs(left); dfs(right);

for(int i = 0; i < tree[left].size(); i++)
for(int j = 0; j < tree[right].size(); j++) {
Tree t;
t.L = max(tree[left][i].L + d1, tree[right][j].L - d2);
t.R = max(tree[right][j].R + d2, tree[left][i].R - d1);
if(t.L + t.R < r) tree[subset].push_back(t);
}
}

if(!have_children) tree[subset].push_back(Tree());
}

int main() {
int T;
scanf("%d", &T);
while(T--) {
scanf("%lf%d", &r, &n);
for(int i = 0; i < n; i++) scanf("%lf", &w[i]);

//打表
for(int i = 0; i < (1<<n); i++) {
sum[i] = 0;
tree[i].clear();
for(int j = 0; j < n; j++)
if(i & (1<<j)) sum[i] += w[j];
}

int root = (1<<n)-1;
memset(vis, 0, sizeof(vis));
dfs(root);

double ans = -1;
for(int i = 0; i < tree[root].size(); i++)
ans = max(ans, tree[root][i].L + tree[root][i].R);
printf("%.10lf\n", ans);
}
return 0;
}