POJ-3126 Prime Path

F - Prime Path (POJ - 3126)

using namespace std;
typedef long long ll;
const int inf = 0x3f3f3f3f;
const int N = 1e5+5;

bool isp[N] = {0};
bool vis[N] = {0};
int n, s, e;

struct P {
    int x;
    int step;
};

void euler() {
    int p[N], m=0;
    for(int i=2; i<=N; i++) {
        if(!isp[i])
            p[m++] = i;
        for(int j=0; j<m; j++) {
            if(p[j]*i>N)
                break;
            isp[p[j]*i] = 1;
            if(i%p[j]==0)
                break;
        }
    }
}

int bfs() {
    memset(vis, 0, sizeof(vis));

    P sp;
    sp.x = s;
    sp.step = 0;

    queue<P> q;
    q.push(sp);
    vis[sp.x] = 1;

    while(!q.empty()) {
        P tp = q.front();
        q.pop();

        if(tp.x==e) {
            return tp.step;
        }
        P np = tp;

        for(int i=1; i<=9; i+=2) {
            np.x = tp.x/10*10 + i;
            if(np.x!=tp.x && !vis[np.x] && !isp[np.x]) {
                np.step = tp.step+1;
                q.push(np);
                vis[np.x] = 1;
            }
        }
        for(int i=0; i<=9; i++) {
            np.x = tp.x/100*100 + i*10 + tp.x%10;
            if(np.x!=tp.x && !vis[np.x] && !isp[np.x]) {
                np.step = tp.step+1;
                q.push(np);
                vis[np.x] = 1;
            }
        }
        for(int i=0; i<=9; i++) {
            np.x = tp.x/1000*1000 + i*100 + tp.x%100;
            if(np.x!=tp.x && !vis[np.x] && !isp[np.x]) {
                np.step = tp.step+1;
                q.push(np);
                vis[np.x] = 1;
            }
        }
        for(int i=1; i<=9; i++) {
            np.x = i*1000 + tp.x%1000;
            if(np.x!=tp.x && !vis[np.x] && !isp[np.x]) {
                np.step = tp.step+1;
                q.push(np);
                vis[np.x] = 1;
            }
        }
    }
    return 0;
}

int main(void) {
    euler();
    scanf("%d", &n);
    for(int i=0; i<n; i++) {
        scanf("%d%d", &s, &e);
        printf("%d\n", bfs());
    }
    return 0;
}

标签：Prime,int,sp,3126,tp,vis,step,POJ
来源： https://blog.csdn.net/IT1656409967/article/details/96964212