Sudoku [Brute force]

#include <stdio.h>

int main(){
    int n, corr = 0;
    scanf("%d", &n);
    for(int tc=1; tc<=n; tc++){
        int board[9][9];
        bool correct = true;
        for(int i=0; i<9 ;i++)
            for(int j=0; j<9; j++)
                scanf("%d", &board[i][j]);
        for(int i=0; i<9 && correct;i++){
            bool flag[10] = {0};
            for(int j=0; j<9; j++){
                if(flag[board[i][j]]){
                    correct = false;
                    break;
                }else{
                    flag[board[i][j]] = true;
                }
            }
        }
        for(int i=0; i<9 && correct;i++){
            bool flag[10] = {0};
            for(int j=0; j<9; j++){
                if(flag[board[j][i]]){
                    correct = false;
                    break;
                }else{
                    flag[board[j][i]] = true;
                }
            }
        }
        for(int i=0; i<9; i+=3){
            for(int j=0; j<9; j+=3){
                bool flag[10] = {0};
                for(int k=i; k<i+3; k++){
                    for(int l=j; l<j+3; l++){
                        if(flag[board[k][l]]){
                            correct = false;
                            break;
                        }else{
                            flag[board[k][l]] = true;
                        }
                    }
                }
            }
        }
        if(correct){
            corr++;
            printf("Case #%d: TRUE\n", tc);
        }else{
            printf("Case #%d: FALSE\n", tc);
        }
    }
    printf("%.2f%%\n", (double)corr*100/n);
    return 0;
}