uva 1376 - Animal Run（最短路）

题目链接：uva 1376 - Animal Run

以每个三角形为一个节点，建图，起点连向左下边界，终点连向右上边界。

#include <cstdio>
#include <cstring>
#include <vector>
#include <queue>
#include <algorithm>

using namespace std;
const int maxn = 2005;
const int maxm = 2 * 1e6 + 5;
const int inf = 0x3f3f3f3f;

struct Dijkstra {
struct Edge {
int u, v, d;
Edge(int u = 0, int v = 0, int d = 0): u(u), v(v), d(d) {}
};

struct State {
int u, d;
State (int u = 0, int d = 0): u(u), d(d) {}
bool operator < (const State& u) const { return d > u.d; }
};

int n, m, dis[maxm], vis[maxm];
vector<Edge> edges;
vector<int> G[maxm];

void init (int n) {
this->n = n;
edges.clear();
for (int i = 0; i < n; i++) G[i].clear();
}

void addEdge(int u, int v, int d) {
edges.push_back(Edge(u, v, d));
m = edges.size();
G[u].push_back(m-1);
}

int dijkstra (int s, int e) {
memset(vis, 0, sizeof(int) * n);
memset(dis, inf, sizeof(int) * n);
dis[s] = 0;

priority_queue<State> que;
que.push(State(s, dis[s]));

while (!que.empty()) {
int u = que.top().u;
que.pop();

if (vis[u]) continue;
vis[u] = 1;

for (int i = 0; i < G[u].size(); i++) {
Edge& edge = edges[G[u][i]];
int v = edge.v, d = edge.d;
if (dis[v] > dis[u] + d) {
dis[v] = dis[u] + d;
que.push(State(v, dis[v]));
}
}
}
return dis[e];
}
}solver;

int N, M, K, id[maxn * 2][maxn];

inline int ID (int x, int y) {
if (y < 0 || x >= 2 * N - 2) return 0;
if (x < 0 || y >= M - 1) return 1;
int& t = id[x][y];
if (t == 0) t = ++K;
return t;
}

void init () {
K = 1;
memset(id, 0, sizeof(id));
int w;

solver.init(2 * ((N-1)*(M-1) + 1));

for (int i = 0; i < N; i++) {
for (int j = 0; j < M-1; j++) {
scanf("%d", &w);
int u = ID(2*i-1, j), v = ID(2*i, j);
solver.addEdge(u, v, w);
solver.addEdge(v, u, w);
}
}

for (int i = 0; i < N-1; i++) {
for (int j = 0; j < M; j++) {
scanf("%d", &w);
int u = ID(2*i+1, j), v = ID(2*i, j-1);
solver.addEdge(u, v, w);
solver.addEdge(v, u, w);
}
}

for (int i = 0;i < N-1; i++) {
for (int j = 0; j < M-1; j++) {
scanf("%d", &w);
int u = ID(2*i, j), v = ID(2*i+1, j);
solver.addEdge(u, v, w);
solver.addEdge(v, u, w);
}
}
}

int main () {
int cas = 1;
while (scanf("%d%d", &N, &M) == 2 && N + M) {
init();
printf("Case %d: Minimum = %d\n", cas++, solver.dijkstra(0, 1));
}
return 0;
}