poj 2488（dfs，存储路径）

#include<iostream>
#include<cstring>
#include<cstdio>
using namespace std;
int row,col,n,k;
int idx[26][26],ansx[900],ansy[900];
void print(){
    printf("%d\n",k);
    for(int i=0;i<col;i++){
        for(int j=0;j<row;j++){
            cout<<idx[i][j]<<" "; 
        }
        cout<<endl;
    }
    cout<<endl;
}
bool dfs(int i,int j,int num){
    idx[i][j] = 1;
//    print();
    if(num==row*col-1){
        return true;
    }
    if(i-2>=0&&j-1>=0&&idx[i-2][j-1]==0){
        ansx[k] = i-2;
        ansy[k] = j-1;
        k++;
        if(dfs(i-2,j-1,num+1))
            return true;
        idx[i-2][j-1] = 0;
        k--;
        ansx[k] = -1;
        ansy[k] = -1;
    }
    if(i-2>=0&&j+1<row&&idx[i-2][j+1]==0){
        ansx[k] = i-2;
        ansy[k] = j+1;
        k++;
        if(dfs(i-2,j+1,num+1))
            return true;
        idx[i-2][j+1] = 0;
        k--;
        ansx[k] = -1;
        ansy[k] = -1;
    }
    if(i-1>=0&&j-2>=0&&idx[i-1][j-2]==0){
        ansx[k] = i-1;
        ansy[k] = j-2;
        k++;
        if(dfs(i-1,j-2,num+1))
            return true;
        idx[i-1][j-2] = 0;
        k--;
        ansx[k] = -1;
        ansy[k] = -1;
    }
    if(i-1>=0&&j+2<row&&idx[i-1][j+2]==0){
        ansx[k] = i-1;
        ansy[k] = j+2;
        k++;
        if(dfs(i-1,j+2,num+1))
            return true;
        idx[i-1][j+2] = 0;
        k--;
        ansx[k] = -1;
        ansy[k] = -1;
    }
    if(i+1<col&&j-2>=0&&idx[i+1][j-2]==0){
        ansx[k] = i+1;
        ansy[k] = j-2;
        k++;
        if(dfs(i+1,j-2,num+1))
            return true;
        idx[i+1][j-2] = 0;
        k--;
        ansx[k] = -1;
        ansy[k] = -1;
    }
    if(i+1<col&&j+2<row&&idx[i+1][j+2]==0){
        ansx[k] = i+1;
        ansy[k] = j+2;
        k++;
        if(dfs(i+1,j+2,num+1))
            return true;
        idx[i+1][j+2] = 0;
        k--;
        ansx[k] = -1;
        ansy[k] = -1;
    }
    if(i+2<col&&j-1>=0&&idx[i+2][j-1]==0){
        ansx[k] = i+2;
        ansy[k] = j-1;
        k++;
        if(dfs(i+2,j-1,num+1))
            return true;
        idx[i+2][j-1] = 0;
        k--;
        ansx[k] = -1;
        ansy[k] = -1;
    }
    if(i+2<col&&j+1<row&&idx[i+2][j+1]==0){
            ansx[k] = i+2;
            ansy[k] = j+1;
            k++;
            if(dfs(i+2,j+1,num+1))
                return true;
            idx[i+2][j+1] = 0;
            k--;
            ansx[k] = -1;
            ansy[k] = -1;
    }
    idx[i][j] = 0; 
    return false;
}
int main(){
    int kase,i;
    scanf("%d",&n);
    for(kase=1;kase<=n;kase++){
        scanf("%d%d",&row,&col);
        memset(idx,0,sizeof(idx));
        memset(ansx,-1,sizeof(ansx));
        memset(ansy,-1,sizeof(ansy));
        printf("Scenario #%d:\n",kase);
        k = 0;
        if(dfs(0,0,0)){
            printf("A1");
            for(i=0;i<k;i++)
                printf("%c%d",ansx[i]+'A',ansy[i]+1);
            printf("\n\n");
        }
        else{
            printf("impossible\n\n");
        }
    }
    return 0;
}