785.cpp

#include <bits/stdc++.h>
using namespace std;
int dx[] = {-1, 0, 0, 1};
int dy[] = {0, -1, 1, 0};
char a[50][90];
int N, M;
char C;
void call(int i, int j, char ch) {
    M = strlen(a[i]);
    if (i < 0 || j < 0 || i >= N || j >= M) return;
    if (a[i][j] != ' ') return;
    a[i][j] = ch;
    for (int k = 0; k < 4; k++) {
        call(i + dx[k], j + dy[k], ch);
    }
    return;
}

int main() {
    // freopen("C:\\Users\\MARUF\\Desktop\\in.txt","r",stdin);
    //   freopen("C:\\Users\\MARUF\\Desktop\\out.txt","w",stdout);
    int n, i, j, k, tc, t = 1;
    i = 0;
    while (gets(a[i])) {
        if (a[i][0] == '_') {
            N = i;
            int flag = 0;
            int m;
            for (i = 0; i < N; i++) {
                m = strlen(a[i]);
                for (j = 0; j < m; j++) {
                    if (a[i][j] != ' ' && a[i][j] != '_' && flag == 0) {
                        C = a[i][j];
                        flag = 1;
                    } else if (a[i][j] != C && a[i][j] != ' ' && flag == 1 && a[i][j] != '_') {
                        char ch = a[i][j];
                        a[i][j] = ' ';
                        call(i, j, ch);
                    }
                }
            }
            for (i = 0; i <= N; i++) puts(a[i]);
            i = 0;
        } else
            i++;
    }
    return 0;
}