ProjectEuler 82

#include <iostream>
#include <cstdio>
#include <algorithm>
#include <queue>
#include <vector>
using namespace std;

const int inf=(-1u)/2;
vector< vector<int> > table;
vector< vector<int> > ansthis;
int n;
int answer=inf;
queue<pair<int,pair<int,int> > > dijq; //inf-distance,x,y

void add(int x,int y,int dist)
{
    dist=inf-dist;
    dijq.push(make_pair(dist,make_pair(x,y)));
}

int getdist()
{
    return inf-dijq.front().first;
}

int getx()
{
    return dijq.front().second.first;
}
int gety()
{
    return dijq.front().second.second;
}
void popit()
{
    dijq.pop();
}

int dijkstra()
{
    int mini=inf;
    while(dijq.empty()==false)
    {
    int distance=getdist();
    int x=getx();
    int y=gety();
    popit();
    if((ansthis[x][y]==-1)^(ansthis[x][y]>distance))
    {
        ansthis[x][y]=distance;
        //make nexts
        if(x!=0)
        add(x-1,y,distance+table[x-1][y]);
        if(x!=n-1)
        add(x+1,y,distance+table[x+1][y]);
        if(y!=n-1)
        add(x,y+1,distance+table[x][y+1]);
        else
        {
            mini=min(mini,distance);
        }
    }
    }//end of while
    return mini;
}

void solve()
{
    for(int i=0;i<n;++i)
    {
        add(i,0,table[i][0]);
        answer=min(answer,dijkstra());
    }
}

void printans()
{
    printf("%d\n",answer);
}

int main()
{
    //scanf("%d",&n);
    n=80;
    table.resize(n);
    ansthis.resize(n);
    for(int i=0;i<n;++i)
    {
        table[i].resize(n);
        ansthis[i].resize(n);
        for(int j=0;j<n;++j)
        {
            scanf("%d",&table[i][j]);
            ansthis[i][j]=-1;
        }
    }
    solve();
    printans();
    return 0;
}