Codeforces Round #289 (Div. 2, ACM ICPC Rules) C. Sums of Digits

#include <iostream>
#include <queue>
#include <stack>
#include <map>
#include <set>
#include <bitset>
#include <cstdio>
#include <algorithm>
#include <cstring>
#include <climits>
#include <cstdlib>
#include <cmath>
#include <time.h>
#define maxn 20005
#define maxm 200005
#define eps 1e-7
#define mod 1000000007
#define INF 0x3f3f3f3f
#define PI (acos(-1.0))
#define lowbit(x) (x&(-x))
#define mp make_pair
#define ls o<<1
#define rs o<<1 | 1
#define lson o<<1, L, mid
#define rson o<<1 | 1, mid+1, R
#define pii pair<int, int>
#pragma comment(linker, "/STACK:16777216")
typedef long long LL;
typedef unsigned long long ULL;
using namespace std;
LL qpow(LL a, LL b){LL res=1,base=a;while(b){if(b%2)res=res*base;base=base*base;b/=2;}return res;}
LL powmod(LL a, LL b){LL res=1,base=a;while(b){if(b%2)res=res*base%mod;base=base*base%mod;b/=2;}return res;}
//head

int a[maxn];
int res[maxn];
int len, n;

void read()
{
scanf("%d", &n);
for(int i = 1; i <= n; i++) scanf("%d", &a[i]);
}

void next(int t)
{
for(int i = 1; t > 0; i++) {
while(res[i] < 9 && t > 0) res[i]++, t--;
len = max(len, i);
}
for(int i = len; i >= 1; i--) printf("%d", res[i]);
printf("\n");
}

void solve(int t)
{
if(t > 0) next(t);
else {
for(int i = 1; i <= len + 1; i++) {
if(t > 0) {
while(res[i] == 9) t += res[i], res[i] = 0, i++;
res[i]++, t--;
if(i == len + 1) len++;
next(t);
break;
}
if(t <= 0) t += res[i], res[i] = 0;
}
}
}

void work()
{
len = 1;
for(int i = 1; i <= n; i++) solve(a[i] - a[i-1]);
}

int main()
{
read();
work();

return 0;
}