FallingBall undone

#include<stdio.h>

int main()
{
    int T;
    scanf("%d",&T);
    for(int t = 1 ; t <= T ; t ++){
        int n;
        scanf("%d",&n);
        int cball[n];
        int sumball = 0;
        for(int i = 0 ; i < n ; i ++){
            scanf("%d",&cball[i]);
            sumball += cball[i];
        }
        if(sumball != n || cball[0] == 0 || cball[n-1] == 0){
            printf("Case #%d: IMPOSSIBLE\n",t);
            continue;
        }
        int nextball = 0;

        char ans[110][n+1];
        for(int i = 0 ; i < 110 ; i++){
            for(int j = 0 ; j < n ; j ++)ans[i][j] = '.';
            ans[i][n] = '\0';
        }
        int maxlevel = 0;
        for(int i = 0 ; i < n ; i ++){
            if(cball[i] == 0)continue;
            int cnt = cball[i];

            if(nextball <= i){ //left
                int level = i - nextball;
                int start = nextball;
                for(int idx = start ; idx <= i; idx ++){
                    if(level != 0)ans[level][idx] = '\\';
                    if(level > maxlevel)maxlevel = level;
                    if(cnt > 0){
                        nextball++;
                        cnt--;
                    }
                    level --;

                }
            }
            if(cnt > 0){ //right
                int level = 1;
                for(int idx = i + 1 ; idx < n && cnt > 0 ; idx ++){
                    ans[level][idx] = '/';
                    if(level > maxlevel)maxlevel = level;
                    nextball = idx + 1;
                    cnt--;
                    level++;
                }
            }

        }
        printf("Case #%d: %d\n",t,maxlevel+1);
        for(int lv = maxlevel ; lv >= 0 ; lv --){
            printf("%s\n",ans[lv]);
        }
    }
    return 0;
}