BZOJ3362 [Usaco2004 Feb]Navigation Nightmare 导航噩梦

标题效果：自脑补。

思维：与维护两个维度和可设置为检查右。

注意，标题给予一堆关系的。我们应该加入两对关系。

Code:

#include <cstdio>

#include <cstring>

#include <cctype>

#include <iostream>

#include <algorithm>

using namespace std;

 

#define N 40010

int n, m;

struct UnionSet {

    int root[N], dis[N];

    void reset() {

        int i;

        for(i = 1; i <= n; ++i)

            root[i] = i, dis[i] = 0;

    }

    int find(int x) {

        static int stack[N];

        int top = 0;

        for(; x != root[x]; x = root[x])

            stack[++top] = x;

        for(int i = top - 1; i >= 1; --i)

            dis[stack[i]] += dis[stack[i + 1]], root[stack[i]] = x;

        return x;

    }

}Set[2];

 

#define K 10010

struct Ask {

    int u, v, tclock, lab;

    void read(int _) {

        lab = _;

        scanf("%d%d%d", &u, &v, &tclock);

    }

    bool operator < (const Ask &B) const {

        return tclock < B.tclock;

    }

}S[K];

int ans[K];

 

#define M 40010

int u[M], v[M], d[M];

bool vec[M];

 

#define _abs(x) ((x)>0?(x):-(x))

 

int main() {

    #ifndef ONLINE_JUDGE

    freopen("tt.in", "r", stdin);

    #endif

     

    scanf("%d%d", &n, &m);

     

    register int i, j;

     

    int a, b, x;

    char s[10];

    for(i = 1; i <= m; ++i) {

        scanf("%d%d%d%s", &a, &b, &x, s);

        d[i] = x;

        if (s[0] == 'E')

            u[i] = a, v[i] = b, vec[i] = 0;

        else if (s[0] == 'W')

            u[i] = b, v[i] = a, vec[i] = 0;

        else if (s[0] == 'N')

            u[i] = a, v[i] = b, vec[i] = 1;

        else

            u[i] = b, v[i] = a, vec[i] = 1;

    }

     

    int Q;

    scanf("%d", &Q);

    for(i = 1; i <= Q; ++i)

        S[i].read(i);

    sort(S + 1, S + Q + 1);

     

    Set[0].reset(), Set[1].reset();

     

    int ra, rb;

    j = 1;

    for(i = 1; i <= m; ++i) {

        ra = Set[vec[i]].find(u[i]);

        rb = Set[vec[i]].find(v[i]);

        Set[vec[i]].root[ra] = rb;

        Set[vec[i]].dis[ra] = d[i] + Set[vec[i]].dis[v[i]] - Set[vec[i]].dis[u[i]];

         

        ra = Set[1 - vec[i]].find(u[i]);

        rb = Set[1 - vec[i]].find(v[i]);

        Set[1 - vec[i]].root[ra] = rb;

        Set[1 - vec[i]].dis[ra] = Set[1 - vec[i]].dis[v[i]] - Set[1 - vec[i]].dis[u[i]];

         

        for(; S[j].tclock == i; ++j) {

            ra = Set[0].find(S[j].u), rb = Set[0].find(S[j].v);

            if (ra != rb) {

                ans[S[j].lab] = -1;

                continue;

            }

            ans[S[j].lab] += _abs(Set[0].dis[S[j].u] - Set[0].dis[S[j].v]);

            ra = Set[1].find(S[j].u), rb = Set[1].find(S[j].v);

            if (ra != rb) {

                ans[S[j].lab] = -1;

                continue;

            }

            ans[S[j].lab] += _abs(Set[1].dis[S[j].u] - Set[1].dis[S[j].v]);

        }

    }

     

    for(i = 1; i <= Q; ++i)

        printf("%d ", ans[i]);

     

    return 0;

}

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