Zero Path (Div2.C) - 최대값, 최소값만 관리하는 테크닉

https://codeforces.com/contest/1695/problem/C

Problem - C - Codeforces

정말 멘탈 많이 나갔었는데 최대값과 최소값만 관리하면 그 사이의 값은 모두 가능하다는 팁을 듣고

10분만에 ac...

멘탈 관리 열심히 해야것다.

import java.util.*;
import java.io.*;

public class q3 {
    static FastScanner fs = new FastScanner();
    static PrintWriter pw = new PrintWriter(System.out);
    static int n, m;
    static boolean[][] map;
    static int[][][] ends;

    public static void main(String[] args) {
        int t = fs.nextInt();
        while (t-- > 0){
            n = fs.nextInt();
            m = fs.nextInt();
            map = new boolean[n][m];
            ends = new int[n][m][2];

            for (int i=0;i<n;i++){
                for (int j=0;j<m;j++){
                    if (fs.nextInt() == 1){
                        map[i][j] = true;
                    }
                }
            }

            if ((n + m) % 2 == 0){
                pw.println("NO");
                continue;
            }

            for (int i=0;i<n;i++){
                for (int j=0;j<m;j++){
                    if (i == 0 && j == 0){
                        if (map[0][0]) ends[0][0][0] = ends[0][0][1] = 1;
                        else ends[0][0][0] = ends[0][0][1] = -1;
                        continue;
                    }
                    int max = Integer.MIN_VALUE, min = Integer.MAX_VALUE, now = -1;
                    if (map[i][j]) now = 1;
                    
                    if (i != 0){
                        max = ends[i - 1][j][0] + now;
                        min = ends[i - 1][j][1] + now;
                    }
                    if (j != 0){
                        max = Math.max(max, ends[i][j - 1][0] + now);
                        min = Math.min(min, ends[i][j - 1][1] + now);
                    }

                    ends[i][j][0] = max;
                    ends[i][j][1] = min;
                }
            }

            int max = ends[n - 1][m - 1][0], min = ends[n - 1][m - 1][1];
            if (max < 0 || min > 0) pw.println("NO");
            else pw.println("YES");
        }

        pw.close();
    }

    // ----------input function----------

    static void sort(int[] a) {
        ArrayList<Integer> L = new ArrayList<>();
        for (int i : a)
            L.add(i);
        Collections.sort(L);
        for (int i = 0; i < a.length; i++)
            a[i] = L.get(i);
    }

    static class FastScanner {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        StringTokenizer st = new StringTokenizer("");

        String next() {
            while (!st.hasMoreTokens()) {
                try {
                    st = new StringTokenizer(br.readLine());
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            return st.nextToken();
        }

        int nextInt() {
            return Integer.parseInt(next());
        }

        double nextDouble() {
            return Double.parseDouble(next());
        }

        int[] readArray(int n) {
            int[] a = new int[n];
            for (int i = 0; i < n; i++)
                a[i] = nextInt();
            return a;
        }

        long nextLong() {
            return Long.parseLong(next());
        }
    }
}