60: noi.ac #69

$code$

#include<iostream>
#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<climits>
using namespace std;
typedef long long LL;
int n, m;
char a[110][110];
bool flg[27];
inline char getans(int x, int y) {
    char ret = a[x][y];
    if (!ret) {
        ret = 'A';
        while (ret == a[x - 1][y] || ret == a[x + 1][y] || ret == a[x][y - 1] || ret == a[x][y + 1]) ++ ret;
    }
    return ret;
}
inline void cover(int x, int y) {
    char c = getans(x, y);
    putchar(c);
    if (a[x][y]) return;
    int sz = 1;
    while(x + sz <= n && y + sz <= m && getans(x, y + sz) == c) {
        sz ++;
    }
    sz --;
    for (int i = x; i <= x + sz; ++ i)
        for (int j = y; j <= y + sz; ++ j)
            a[i][j] = c;
}

int main() {
    scanf("%d%d", &n, &m);
    for (int i = 1; i <= n; ++ i) {
        for (int j = 1; j <= m; ++ j)
            cover(i, j);
        putchar('\n');
    }
}