Codeforces 585D Lizard Era: Beginning

Lizard Era: Beginning 

折半之后搜就完事了， 直接存string字符串卡空间， 随便卡卡空间吧。

#include<bits/stdc++.h>
#define LL long long
#define fi first
#define se second
#define mk make_pair
#define PLL pair<LL, LL>
#define PLI pair<LL, int>
#define PII pair<int, int>
#define SZ(x) ((int)x.size())
#define ull unsigned long long
using namespace std;

const int N = 25;
const int inf = 0x3f3f3f3f;
const LL INF = 0x3f3f3f3f3f3f3f3f;
const int mod = 1e9 + 7;
const double eps = 1e-8;

int n, L[N], M[N], W[N];
vector<int> vc1, vc2;

struct Node {
    int L, M, W;
    char s[13][2];
};
vector<Node> tmp;
map<pair<PII,int>, int> Map;

Node t, ans1, ans2;

void dfs(int x) {
    if(x == SZ(vc1)) {
        int who = SZ(tmp);
        tmp.push_back(t);
        int mn = min(t.L, min(t.M, t.W));
        auto it = Map.find(mk(mk(t.L-mn, t.M-mn), t.W-mn));
        if(it == Map.end() || tmp[it->se].L < tmp[who].L)
            Map[mk(mk(t.L-mn, t.M-mn), t.W-mn)] = who;
        return;
    }
    t.L += L[vc1[x]]; t.M += M[vc1[x]]; t.s[x][0] = 'L', t.s[x][1] = 'M';
    dfs(x + 1);
    t.L -= L[vc1[x]]; t.M -= M[vc1[x]];

    t.L += L[vc1[x]]; t.W += W[vc1[x]]; t.s[x][0] = 'L', t.s[x][1] = 'W';
    dfs(x + 1);
    t.L -= L[vc1[x]]; t.W -= W[vc1[x]];

    t.M += M[vc1[x]]; t.W += W[vc1[x]]; t.s[x][0] = 'M', t.s[x][1] = 'W';
    dfs(x + 1);
    t.M -= M[vc1[x]]; t.W -= W[vc1[x]];
}

void dfs2(int x) {
    if(x == SZ(vc2)) {
        int mn = min(t.L, min(t.M, t.W));
        int mx = max(t.L-mn, max(t.M-mn, t.W-mn));
        auto it = Map.find(mk(mk(mx-t.L+mn, mx-t.M+mn), mx-t.W+mn));
        if(it == Map.end()) return;
        int id = it->se;
        if(t.L + tmp[id].L > ans1.L + ans2.L) {
            ans1 = tmp[id];
            ans2 = t;
        }
        return;
    }
    t.L += L[vc2[x]]; t.M += M[vc2[x]]; t.s[x][0] = 'L', t.s[x][1] = 'M';
    dfs2(x + 1);
    t.L -= L[vc2[x]]; t.M -= M[vc2[x]];

    t.L += L[vc2[x]]; t.W += W[vc2[x]]; t.s[x][0] = 'L', t.s[x][1] = 'W';
    dfs2(x + 1);
    t.L -= L[vc2[x]]; t.W -= W[vc2[x]];

    t.M += M[vc2[x]]; t.W += W[vc2[x]]; t.s[x][0] = 'M', t.s[x][1] = 'W';
    dfs2(x + 1);
    t.M -= M[vc2[x]]; t.W -= W[vc2[x]];
}

int main() {
    cin >> n;
    for(int i = 0; i < n; i++)
        cin >> L[i] >> M[i] >> W[i];
    if(n == 1) {
        if(!L[0] && !M[0]) puts("LM");
        else if(!L[0] && !W[0]) puts("LW");
        else if(!M[0] && !W[0]) puts("MW");
        else puts("Impossible");
        return 0;
    }
    int c = n >> 1;
    for(int i = 0; i < c; i++) vc1.push_back(i);
    for(int i = c; i < n; i++) vc2.push_back(i);

    ans1.L = -inf; ans2.L = -inf;
    dfs(0);
    dfs2(0);

    if(ans1.L <= -inf) {
        puts("Impossible");
        return 0;
    }
    for(int i = 0; i < c; i++) cout << ans1.s[i][0] << ans1.s[i][1] << "
";
    for(int i = 0; i < n - c; i++) cout << ans2.s[i][0] << ans2.s[i][1] << "
";
    return 0;
}

/*
*/