Go: ///
// File:  0558.go
// Author: ymiyamoto
//
// Created on Sun Mar  4 20:58:45 2018
//
package main

import (
	"fmt"
	"strconv"
	"strings"
)

type pos struct {
	x, y int
}

var H, W, N int
var graph [][]string

func wfs(p pos, index int) (int, pos) {
	var q []pos
	dists := make([][]int, H)
	for i := range dists {
		dists[i] = make([]int, W)
	}

	q = append(q, p)
	for len(q) > 0 {
		p := q[0]
		dist := dists[p.x][p.y]
		q = q[1:]

		for _, d := range []pos{{-1, 0}, {1, 0}, {0, -1}, {0, 1}} {
			x := p.x + d.x
			y := p.y + d.y
			if 0 <= x && x < H && 0 <= y && y < W && graph[x][y] != "X" && dists[x][y] == 0 {
				dists[x][y] = dist + 1
				q = append(q, pos{x, y})
			}
		}
	}

	for i := range graph {
		for j := range graph[i] {
			if graph[i][j] == strconv.Itoa(index) {
				return dists[i][j], pos{i, j}
			}
		}
	}

	panic("not found")
}

func main() {
	fmt.Scan(&H, &W, &N)

	var start pos

	graph = make([][]string, H)
	for i := range graph {
		var s string
		fmt.Scan(&s)
		graph[i] = strings.Split(s, "")
		for j := range graph[i] {
			if graph[i][j] == "S" {
				start.x = i
				start.y = j
			}
		}
	}

	count := 0
	for i := 1; i <= N; i++ {
		c, s := wfs(start, i)
		start = s
		count += c
	}

	fmt.Println(count)
}

C++: #include <cassert>// c
#include <iostream>// io
#include <iomanip>
#include <fstream>
#include <sstream>
#include <vector>// container
#include <map>
#include <set>
#include <queue>
#include <bitset>
#include <stack>
#include <algorithm>// other
#include <complex>
#include <numeric>
#include <functional>
#include <random>
#include <regex>
using namespace std;

typedef long long ll;

#define ALL(c) (begin(c)),(end(c))
#define REP(i,n) FOR(i,0,n)
#define REPr(i,n) FORr(i,0,n)
#define FOR(i,l,r) for(int i=(int)(l);i<(int)(r);++i)
#define FORr(i,l,r) for(int i=(int)(r)-1;i>=(int)(l);--i)
#define EACH(it,o) for(auto it = (o).begin(); it != (o).end(); ++it)
#define IN(l,v,r) ((l)<=(v) && (v)<(r))
#define UNIQUE(v) v.erase(unique(ALL(v)),v.end())
//debug
#define DUMP(x)  cerr << #x << " = " << (x)
#define LINE()    cerr<< " (L" << __LINE__ << ")"

class range {
private:
	struct Iter{
		int v;
		int operator*(){return v;}
		bool operator!=(Iter& itr) {return v < itr.v;}
		void operator++() {++v;}
	};
	Iter i, n;
public:
	range(int n) : i({0}), n({n}) {}
	range(int i, int n) : i({i}), n({n}) {}
	Iter& begin() {return i;}
	Iter& end() {return n;}
};

//output
template<typename T> ostream& operator << (ostream& os, const vector<T>& as){REP(i,as.size()){if(i!=0)os<<" "; os<<as[i];}return os;}
template<typename T> ostream& operator << (ostream& os, const vector<vector<T>>& as){REP(i,as.size()){if(i!=0)os<<endl; os<<as[i];}return os;}
template<typename T> ostream& operator << (ostream& os, const set<T>& ss){for(auto a:ss){if(a!=ss.begin())os<<" "; os<<a;}return os;}
template<typename T1,typename T2> ostream& operator << (ostream& os, const pair<T1,T2>& p){os<<p.first<<" "<<p.second;return os;}
template<typename K,typename V> ostream& operator << (ostream& os, const map<K,V>& m){bool isF=true;for(auto& p:m){if(!isF)os<<endl;os<<p;isF=false;}return os;}
template<typename T1> ostream& operator << (ostream& os, const tuple<T1>& t){os << get<0>(t);return os;}
template<typename T1,typename T2> ostream& operator << (ostream& os, const tuple<T1,T2>& t){os << get<0>(t)<<" "<<get<1>(t);return os;}
template<typename T1,typename T2,typename T3> ostream& operator << (ostream& os, const tuple<T1,T2,T3>& t){os << get<0>(t)<<" "<<get<1>(t)<<" "<<get<2>(t);return os;}
template<typename T1,typename T2,typename T3,typename T4> ostream& operator << (ostream& os, const tuple<T1,T2,T3,T4>& t){os << get<0>(t)<<" "<<get<1>(t)<<" "<<get<2>(t)<<" "<<get<3>(t);return os;}
template<typename T1,typename T2,typename T3,typename T4,typename T5> ostream& operator << (ostream& os, const tuple<T1,T2,T3,T4,T5>& t){os << get<0>(t)<<" "<<get<1>(t)<<" "<<get<2>(t)<<" "<<get<3>(t)<<" "<<get<4>(t);return os;}
template<typename T1,typename T2,typename T3,typename T4,typename T5,typename T6> ostream& operator << (ostream& os, const tuple<T1,T2,T3,T4,T5,T6>& t){os << get<0>(t)<<" "<<get<1>(t)<<" "<<get<2>(t)<<" "<<get<3>(t)<<" "<<get<4>(t)<<" "<<get<5>(t);return os;}
template<typename T1,typename T2,typename T3,typename T4,typename T5,typename T6,typename T7> ostream& operator << (ostream& os, const tuple<T1,T2,T3,T4,T5,T6,T7>& t){os << get<0>(t)<<" "<<get<1>(t)<<" "<<get<2>(t)<<" "<<get<3>(t)<<" "<<get<4>(t)<<" "<<get<5>(t)<<" "<<get<6>(t);return os;}

//input
char tmp[1000];
#define nextInt(n) scanf("%d",&n)
#define nextLong(n) scanf("%lld",&n) //I64d
#define nextDouble(n) scanf("%lf",&n) 
#define nextChar(n) scanf("%c",&n)
#define nextString(n) scanf("%s",tmp);n=tmp

// values
template<typename T> T INF(){assert(false);};
template<> int INF<int>(){return 1<<28;};
template<> ll INF<ll>(){return 1LL<<58;};
template<> double INF<double>(){return 1e16;};

template<class T> T EPS(){assert(false);};
template<> int EPS<int>(){return 1;};
template<> ll EPS<ll>(){return 1LL;};
template<> double EPS<double>(){return 1e-8;};
template<> long double EPS<long double>(){return 1e-8;};


template<typename T,typename U> T pmod(T v,U M){return (v%M+M)%M;}

int dx[4]={1,0,-1,0},dy[4]={0,1,0,-1};
class Main{
	public:
	void run(){
	    int H,W,N;cin >> H >> W >> N;
	    vector<string> board(H);
	    REP(i,H)cin >> board[i];

	    int sy,sx;
	    REP(y,H)REP(x,W)if(board[y][x]=='S'){
	    	sy=y;sx=x;
	    }
	    //bool passed[H][W][N+1]  くそ最適化
	    int passed[H][W]; 
		REP(y,H)REP(x,W)passed[y][x]=0;
	    queue<tuple<int,int,int,int>> que;
	    que.push(make_tuple(sy,sx,0,0));
	    passed[sy][sx]|=(1<<0);
	    int res=INF<int>();
	    while(!que.empty()){
	    	auto t = que.front();que.pop();
	    	int y,x,n,c;tie(y,x,n,c)=t;
	    	if(n==N){
	    	    res=min(res,c);break;
	    	}
	    	REP(d,4){
	    	    int nx=x+dx[d],ny=y+dy[d];
	    	    if(IN(0,nx,W) && IN(0,ny,H)){
		    		if(board[ny][nx]==(n+1)+'0' && n+1<=N){
		    		    if(!(passed[ny][nx]&(1<<(n+1)))){
		    		    	que.push(make_tuple(ny,nx,n+1,c+1));
		    		    	passed[ny][nx]|=1<<(n+1);
		    		    }
		    		}else if(board[ny][nx]!='X'){
		    		    if(!(passed[ny][nx]&(1<<n))){
			    		    que.push(make_tuple(ny,nx,n,c+1));
		    		    	passed[ny][nx]|=1<<n;
						}
		    		}
	    	    }
	    	}		
	    }
	    cout << res << endl;
	}
};

int main(){
	cout <<fixed<<setprecision(20);
	cin.tie(0);
	ios::sync_with_stdio(false);
	Main().run();
	return 0;
}

C++: #include<iostream>
#include<queue>
using namespace std;
struct Point{int x,y,dist;};
int main()
{
  int H,W,N;
  int vital;
  int i,j;
  string field[1000];
  int dx[4]={0,1,0,-1};
  int dy[4]={-1,0,1,0};
  Point ans;

  cin>>H>>W>>N;
  for(i=0;i<H;i++)cin>>field[i];
  for(i=0;i<H;i++){
    for(j=0;j<W;j++){
      if(field[i][j]=='S'){
	ans.y=i;
	ans.x=j;
	ans.dist=0;
      }
    }
  }

  for(vital=1;vital<=N;vital++){
    queue<Point>q;
    bool visited[1000][1000]={0};
    bool f=0;

    q.push(ans);
    while(!f){
      Point p=q.front();
      q.pop();
      visited[p.y][p.x]=true;

      for(i=0;i<4;i++){
	Point p2;
	p2.y=p.y+dy[i];
	p2.x=p.x+dx[i];
	p2.dist=p.dist+1;
	if(p2.y<0||H<=p2.y)continue;
	if(p2.x<0||W<=p2.x)continue;
	if(field[p2.y][p2.x]=='X')continue;
	if(visited[p2.y][p2.x])continue;
	if(field[p2.y][p2.x]==(vital+'0')){
	  ans=p2;
	  f=1;
	  break;
	}
	q.push(p2);
      }
    }
  }
  cout<<ans.dist<<endl;
}