牛客国庆集训派对Day3 A Knight

Knight

思路：

bfs打表找规律

如下图

代码：

#pragma GCC optimize(2)
#pragma GCC optimize(3)
#pragma GCC optimize(4)
#include<bits/stdc++.h>
using namespace std;
#define fi first
#define se second
#define pi acos(-1.0)
#define LL long long
//#define mp make_pair
#define pb push_back
#define ls rt<<1, l, m
#define rs rt<<1|1, m+1, r
#define ULL unsigned LL
#define pll pair<LL, LL>
#define pii pair<int, int>
#define piii pair<pii, int>
#define mem(a, b) memset(a, b, sizeof(a))
#define fio ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);
#define fopen freopen("in.txt", "r", stdin);freopen("out.txt", "w", stout);
//head

int n, m;
int dir[8][2] = {
  2, 1, 1, 2, 2, -1, -1, 2, -2, 1, 1, -2, -2, -1, -1, -2
};
int res[5][5] = {
    {0, 3, 2, 3, 2},
    {3, 2, 1, 2, 3},
    {2, 1, 4, 3, 2},
    {3, 2, 3, 2, 3},
    {2, 3, 2, 3, 4}
};
map<pii, bool> vis;
int bfs() {
    queue<piii> q;
    q.push(piii{{0, 0}, 0});
    vis.clear();
    vis[pii{0, 0}] = true;
    while(!q.empty()) {
        piii now = q.front();
        q.pop();
        if(now.fi.fi == n && now.fi.se == m) return now.se;
        for (int i = 0; i < 8; i++) {
            int x = now.fi.fi + dir[i][0];
            int y = now.fi.se + dir[i][1];
            if(vis.find(pii{x, y}) == vis.end()) {
                vis[pii{x, y}] = true;
                q.push({{x, y}, now.se+1});
            }
        }
    }
    return 0;
}
int main() {
    int T;
//    for (n = 0; n <= 20; n++) {
//        for (m = 0; m <= 20; m++) {
//            cout<< setw(4) << bfs();
//        }
//        cout << endl;
//    }
    scanf("%d", &T);
    while(T--) {
        scanf("%d %d", &n, &m);
        n = abs(n);
        m = abs(m);
        if(n <= 4 && m <= 4) {
            printf("%d
", res[n][m]);
            continue;
        }
        if(n > m) swap(n, m);
        if(m <= 2*n) {
            printf("%d
", (m+n)/3 + (m+n)%3);
        }
        else {
            if(n == 0) printf("%d
", (m+2)/4*2 + m%2);
            else printf("%d
", (m-2*n)/4*2 + n + (m-2*n)%4);
        }
    }
    return 0;
}