HDU 4433 locker

题意：A password locker with N digits, each digit can be rotated to 0-9 circularly.
You can rotate 1-3 consecutive digits up or down in one step.
For examples:

567890 -> 567901 (by rotating the last 3 digits up)

000000 -> 000900 (by rotating the 4th digit down)

Given the current state and the secret password, what is the minimum amount of steps

you have to rotate the locker in order to get from current state to the secret password?

#include <iostream>
#include <string>
#include <cstring>
#include <cstdio>
#define maxn 1100
#define inf 1000000
using namespace std;

char s1[maxn];
char s2[maxn];
int   a[maxn];
int   b[maxn];
int up[12][12];
int down[12][12];
int dp[maxn][12][12];
int n;

void init()
{
int i,j;
for(i=0;i<=9;i++)
{
for(j=0;j<=9;j++)
{
up[i][j]=j>=i?j-i:10+(j-i);
down[i][j]=j<=i?i-j:10+i-j;
}
}
}

int main()
{
init();
int i,j,k;
int ii,jj;
while(~scanf("%s %s",&s1, &s2))
{
n = strlen(s1);
for(i=0;i<=n+3;i++)
{
for(j=0;j<=9;j++)
{
for(k=0;k<=9;k++)
{
dp[i][j][k]=inf;
}
}
}

for(i=0; i<n; i++)
{
a[i] = s1[i]-'0';
b[i] = s2[i]-'0';
}
a[i] = a[i+1] = b[i] = b[i+1] = 0;
dp[0][a[0]][a[1]]=0;

for(i=1; i<=n; i++)
{
for(j=0; j<=9; j++)
{
for(k=0; k<=9; k++)
{
int temp=up[j][b[i-1]];
for(ii=0; ii<=temp; ii++)
{
for(jj=0; jj<=ii; jj++)
{
dp[i][(k+ii)%10][(a[i+1]+jj)%10]=
min(dp[i][(k+ii)%10][(a[i+1]+jj)%10],dp[i-1][j][k]+temp);
}
}

temp=down[j][b[i-1]];
for(ii=0;ii<=temp;ii++)
{
for(jj=0;jj<=ii;jj++)
{
dp[i][(k-ii+10)%10][(a[i+1]-jj+10)%10]=
min(dp[i][(k-ii+10)%10][(a[i+1]-jj+10)%10],dp[i-1][j][k]+temp);
}
}
}
}
}
printf("%d\n",dp
[0][0]);
}
return 0;
}