Lưu ý: Các code mẫu dưới đây chỉ mang tính tham khảo và có thể không AC được bài tập này

Code mẫu của ladpro98

program NKTABLE;
uses    math;
const   maxn=555;
        fi='';
        dx:array[1..2] of longint = (0,1);
        dy:array[1..2] of longint = (1,0);
type    e=record
                x,y:longint;
        end;
var     a:array[1..maxn,1..maxn] of longint;
        q:array[1..2*maxn*maxn] of e;
        res:array[1..maxn+maxn] of longint;
        chk,chk2:array[1..maxn,1..maxn] of boolean;
        m,n,l,r,layer:longint;

procedure input;
var     inp:text;
        i,j:longint;
begin
        assign(inp,fi);reset(inp);
        readln(inp,m,n);
        for i:=1 to m do
        for j:=1 to n do read(inp,a[i,j]);
        close(inp);
end;

procedure bfsChk;
var     l,r,i,x,y:longint;
        u:e;
begin
        l:=1;r:=1;
        q[1].x:=m;q[1].y:=n;
        chk[m,n]:=true;
        while l<=r do begin
                u:=q[l];inc(l);
                for i:=1 to 2 do begin
                        x:=u.x-dx[i];
                        y:=u.y-dy[i];
                        if (0<x) and (0<y) and (x<=m) and (y<=n)
                        and (not chk[x,y]) and (a[x,y]<2) then begin
                                inc(r);
                                q[r].x:=x;
                                q[r].y:=y;
                                chk[x,y]:=true;
                        end;
                end;
        end;
end;

function bfs:boolean;
var     i,j,x,y:longint;
        u:e;
        found:boolean;
begin
        j:=r;
        found:=false;
        while l<=r do begin
                u:=q[l];inc(l);
                for i:=1 to 2 do begin
                        x:=u.x+dx[i];
                        y:=u.y+dy[i];
                        if (0<x) and (0<y) and (x<=m) and (y<=n)
                        and (chk[x,y]) and (not chk2[x,y]) and (a[x,y]<2) then begin
                                if a[x,y] = 1 then found:=true;
                                chk2[x,y]:=true;
                                inc(j);
                                q[j].x:=x;
                                q[j].y:=y;
                        end;
                end;
        end;
        r:=j;
        exit(found);
end;

procedure resetQueue;
var     tl,tr,i:longint;
begin
        tl:=l;tr:=r;
        l:=1;r:=0;
        for i:=tl to tr do
        if a[q[i].x,q[i].y]=1 then begin
                inc(r);
                q[r]:=q[i];
        end;
end;

begin
        input;
        bfsChk;
        l:=1;r:=1;q[1].x:=1;q[1].y:=1;
        res[1]:=a[1,1];
        for layer:=2 to m+n-1 do begin
                if bfs then begin
                        res[layer]:=1;
                        resetQueue;
                end
                else    res[layer]:=0;
        end;
        for layer:=1 to m+n-1 do write(res[layer]);
end.

Code mẫu của RR

#include <sstream>
#include <iomanip>
#include <iostream>
#include <cstdio>
#include <cstring>
#include <cstdlib>
#include <cmath>
#include <algorithm>
#include <vector>
#include <set>
#include <map>
#include <stack>
#include <queue>
#include <string>
#include <deque>
#include <complex>

#define FOR(i,a,b) for(int i=(a),_b=(b); i<=_b; i++)
#define FORD(i,a,b) for(int i=(a),_b=(b); i>=_b; i--)
#define REP(i,a) for(int i=0,_a=(a); i<_a; i++)
#define FORN(i,a,b) for(int i=(a),_b=(b);i<_b;i++)
#define DOWN(i,a,b) for(int i=a,_b=(b);i>=_b;i--)
#define SET(a,v) memset(a,v,sizeof(a))
#define sqr(x) ((x)*(x))
#define ll long long
#define F first
#define S second
#define PB push_back
#define MP make_pair

#define DEBUG(x) cout << #x << " = "; cout << x << endl;
#define PR(a,n) cout << #a << " = "; FOR(_,1,n) cout << a[_] << ' '; cout << endl;
#define PR0(a,n) cout << #a << " = "; REP(_,n) cout << a[_] << ' '; cout << endl;
using namespace std;

//Buffer reading
int INP,AM,REACHEOF;
#define BUFSIZE (1<<12)
char BUF[BUFSIZE+1], *inp=BUF;
#define GETCHAR(INP) { \
    if(!*inp) { \
        if (REACHEOF) return 0;\
        memset(BUF,0,sizeof BUF);\
        int inpzzz = fread(BUF,1,BUFSIZE,stdin);\
        if (inpzzz != BUFSIZE) REACHEOF = true;\
        inp=BUF; \
    } \
    INP=*inp++; \
}
#define DIG(a) (((a)>='0')&&((a)<='9'))
#define GN(j) { \
    AM=0;\
    GETCHAR(INP); while(!DIG(INP) && INP!='-') GETCHAR(INP);\
    if (INP=='-') {AM=1;GETCHAR(INP);} \
    j=INP-'0'; GETCHAR(INP); \
    while(DIG(INP)){j=10*j+(INP-'0');GETCHAR(INP);} \
    if (AM) j=-j;\
}
//End of buffer reading

const long double PI = acos((long double) -1.0);
typedef pair<int,int> P;

const int di[] = {0,1};
const int dj[] = {1,0};

int m, n, a[511][511];
P tr[511][511];
queue< P > cur, next[2];
deque< queue<P> > v;

bool inside(int u, int v) {
    return (u > 0) && (u <= m) && (v > 0) && (v <= n);
}

void clear(queue< P > &q) {
    while (!q.empty()) q.pop();
}

void trace(int m, int n) {
    if (m == 1 && n == 1) {
        printf("%d", a[1][1]);
        return ;
    }
    trace(tr[m][n].F, tr[m][n].S);
    printf("%d", a[m][n]);
}

int main() {
    scanf("%d%d", &m, &n);
    FOR(i,1,m) FOR(j,1,n) scanf("%d", &a[i][j]);

    clear(cur); cur.push(MP(1,1));
    v.push_back(cur);

    while (!v.empty()) {
        cur = v.front();
        clear(next[0]); clear(next[1]);
        while (!cur.empty()) {
            P u = cur.front(); cur.pop();
            REP(dir,2) {
                P v = MP(u.F + di[dir], u.S + dj[dir]);
                if (inside(v.F, v.S) && a[v.F][v.S] < 2 && tr[v.F][v.S] == MP(0,0)) {
                    tr[v.F][v.S] = u;
                    next[a[v.F][v.S]].push(v);
                }
            }
        }
        if (!next[1].empty()) v.push_back(next[1]);
        if (!next[0].empty()) v.push_back(next[0]);
        v.pop_front();
    }
    trace(m, n);
    puts("");
    return 0;
}

Code mẫu của hieult

#include <set>
#include <map>
#include <list>
#include <cmath>
#include <ctime>
#include <deque>
#include <queue>
#include <stack>
#include <bitset>
#include <cctype>
#include <cstdio>
#include <string>
#include <vector>
#include <cassert>
#include <cstdlib>
#include <cstring>
#include <sstream>
#include <iomanip>
#include <iostream>
#include <algorithm>

using namespace std;

typedef long long ll;
typedef long double ld;
typedef unsigned int ui;
typedef unsigned long long ull;

#define Rep(i,n) for(typeof(n) i = 0; i < (n); ++i)
#define Repd(i,n) for(typeof(n) i = (n)-1; i >= 0; --i)
#define For(i,a,b) for(typeof(b) i = (a); i <= (b); ++i)
#define Ford(i,a,b) for(typeof(a) i = (a); i >= (b); --i)
#define Fit(i,v) for(typeof((v).begin()) i = (v).begin(); i != (v).end(); ++i)
#define Fitd(i,v) for(typeof((v).rbegin()) i = (v).rbegin(); i != (v).rend(); ++i)
#define mp make_pair
#define pb push_back
#define fi first
#define se second
#define sz(a) ((int)(a).size())
#define all(a) (a).begin(), (a).end()
#define ms(a,x) memset(a, x, sizeof(a))
#define nl puts("")
#define sp printf(" ")
#define ok puts("ok")
//#include <conio.h>

template<class F, class T> T convert(F a, int p = -1) { stringstream ss; if (p >= 0) ss << fixed << setprecision(p); ss << a; T r; ss >> r; return r; }
template<class T> void db(T a, int p = -1) { if (p >= 0) cout << fixed << setprecision(p); cout << a << " "; }
template<class T> T gcd(T a, T b) { T r; while (b != 0) { r = a % b; a = b; b = r; } return a; }
template<class T> T lcm(T a, T b) { return a / gcd(a, b) * b; }
template<class T> T sqr(T x) { return x * x; }
template<class T> T cube(T x) { return x * x * x; }
template<class T> struct Triple { T x, y, z; Triple() {} Triple(T _x, T _y, T _z) : x(_x), y(_y), z(_z) {} };
template<class T> Triple<T> euclid(T a, T b) { if (b == 0) return Triple<T>(1, 0, a); Triple<T> r = euclid(b, a % b); return Triple<T>(r.y, r.x - a / b * r.y, r.z); }
template<class T> int getbit(T s, int i) { return (s >> i) & 1; }
template<class T> T onbit(T s, int i) { return s | (T(1) << i); }
template<class T> T offbit(T s, int i) { return s & (~(T(1) << i)); }
template<class T> int cntbit(T s) { return s == 0 ? 0 : cntbit(s >> 1) + (s & 1); }
const int bfsz = 1 << 16; char bf[bfsz + 5]; int rsz = 0;int ptr = 0;
char gc() { if (rsz <= 0) { ptr = 0; rsz = fread(bf, 1, bfsz, stdin); if (rsz <= 0) return EOF; } --rsz; return bf[ptr++]; }
void ga(char &c) { c = EOF; while (!isalpha(c)) c = gc(); }
int gs(char s[]) { int l = 0; char c = gc(); while (isspace(c)) c = gc(); while (c != EOF && !isspace(c)) { s[l++] = c; c = gc(); } s[l] = '\0'; return l; }
template<class T> bool gi(T &v) {
    v = 0; char c = gc(); while (c != EOF && c != '-' && !isdigit(c)) c = gc(); if (c == EOF) return false; bool neg = c == '-'; if (neg) c = gc();
    while (isdigit(c)) { v = v * 10 + c - '0'; c = gc(); } if (neg) v = -v; return true;
}

const double PI = 2 * acos(0);
const string months[] = {"January", "February", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December"};
const int days[] = {31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
const int dr[] = {0, +1};
const int dc[] = {+1, 0};
const int inf = (int)1e9 + 5;
const ll linf = (ll)1e16 + 5;
const double eps = 1e-9;
const ll mod = 100000007;
typedef pair<int, int> II;

#define maxn 505
#define maxe 100005

int n, m, a[maxn][maxn];
int test;
bool b[maxn][maxn], g[maxn][maxn];

bool thoaman(int r, int c){
    return (r > 0 && r <= n && c > 0 && c <= m && a[r][c] != 2);
}

void dfs(int r, int c){
   // printf("%d %d\n", r, c);
    int rr, cc;
    Rep(t, 2){
        rr = r - dr[t];
        cc = c - dc[t];
        if(thoaman(rr, cc) && ! b[rr][cc]){
            b[rr][cc] = 1;
            dfs(rr, cc);
        }
    }
}

int main() {
//    freopen("in.txt", "r", stdin);
//    freopen("out.txt", "w", stdout);
    ms(b, 0); ms(g, 0);
    scanf("%d %d", &n, &m);
    For(i, 1, n) For(j, 1, m) scanf("%d", &a[i][j]);
    b[n][m] = 1;
    dfs(n, m);
    vector<int> res;
    res.pb(a[1][1]); g[1][1] = 1;
    int j, r, c;

    For(add, 2, n + m - 1){
        int MAX = 0;
        queue<II> q;
        for(int i = 1; i <= n && i < add; i++){
            j = add - i;
            if(thoaman(i, j) && g[i][j]){
               // printf("%d %d\n", i, j);
                Rep(t, 2){
                    r = i + dr[t];
                    c = j + dc[t];
                    if(thoaman(r, c) && b[r][c]){
                        MAX = max(MAX, a[r][c]);
                        q.push(mp(r, c));
                    }
                }
            }
        }
        res.pb(MAX);
        while(!q.empty()){
            r = q.front().fi; c = q.front().se; q.pop();
            if(a[r][c] == MAX) g[r][c] = 1;
        }
    }
    Rep(i, sz(res)) printf("%d", res[i]);
   // cout << clock() << endl;
    return 0;
}

Code mẫu của skyvn97

#include<bits/stdc++.h>
#define MAX   505
struct pos {
    int x,y;
    pos(){}
    pos(const int &_x,const int &_y) {
        x=_x;y=_y;
    }
};
int a[MAX][MAX];
bool mv[MAX][MAX];
bool vs[MAX][MAX];
int m,n;
int res[2*MAX];
pos v[2][2*MAX];
int sz[2];
void init(void) {
    scanf("%d",&m);
    scanf("%d",&n);
    int i,j;
    for (i=1;i<=m;i=i+1)
        for (j=1;j<=n;j=j+1)
            scanf("%d",&a[i][j]);   
}
void optimize(void) {
    int i,j;
    mv[m][n]=true;
    vs[m][n]=false;
    for (i=m;i>=1;i=i-1)
        for (j=n-(i==m);j>=1;j=j-1) {
            if (a[i][j]==2) mv[i][j]=false;
            else mv[i][j]=mv[i+1][j]||mv[i][j+1];
            vs[i][j]=false;
        }
    for (i=0;i<=m+1;i=i+1) {
        mv[i][0]=false;
        mv[i][n+1]=false;
    }
    for (i=0;i<=n+1;i=i+1) {
        mv[0][i]=false;
        mv[m+1][i]=false;
    }
}
void BFS(void) {
    int st,i,t,mval;
    sz[1]=1;
    v[1][1]=pos(1,1);
    res[1]=a[1][1];
    for (st=1;st<m+n-1;st=st+1) {
        t=st%2;
        mval=0;
        for (i=1;i<=sz[t];i=i+1) {          
            if (mv[v[t][i].x+1][v[t][i].y] && mval<a[v[t][i].x+1][v[t][i].y]) mval=a[v[t][i].x+1][v[t][i].y];
            if (mv[v[t][i].x][v[t][i].y+1] && mval<a[v[t][i].x][v[t][i].y+1]) mval=a[v[t][i].x][v[t][i].y+1];
        }
        res[st+1]=mval;
        sz[1-t]=0;
        for (i=1;i<=sz[t];i=i+1) {
            if (!vs[v[t][i].x+1][v[t][i].y] && mv[v[t][i].x+1][v[t][i].y] && mval==a[v[t][i].x+1][v[t][i].y]) {
                sz[1-t]++;
                v[1-t][sz[1-t]]=pos(v[t][i].x+1,v[t][i].y);
                vs[v[t][i].x+1][v[t][i].y]=true;
            }
            if (!vs[v[t][i].x][v[t][i].y+1] && mv[v[t][i].x][v[t][i].y+1] && mval==a[v[t][i].x][v[t][i].y+1]) {
                sz[1-t]++;
                v[1-t][sz[1-t]]=pos(v[t][i].x,v[t][i].y+1);
                vs[v[t][i].x][v[t][i].y+1]=true;
            }
        }
    }
    for (st=1;st<m+n;st=st+1) printf("%d",res[st]);
}
int main(void) {
    init();
    optimize();
    BFS();
    return 0;
}