hdu 2544 最短路 (Dijstra + Heap優化)

題目鏈接：HDU 2544

#include <cstdio>
#include <cstring>
#include <queue>
using namespace std;

const int maxn = 11111;
const int inf = (int)1e9;

struct Edge
{
    int v, next;  // v 邊所指向的節點 next 邊所指向的節點的指針
    int cost;     // 權值
    Edge() {}
    Edge(int a, int b) { v = a, cost = b; }
    bool operator<(const Edge & x)const {
        return cost > x.cost;
    }
} edge[maxn];

int eh[maxn], tot, dist[maxn];   // eh[i] 指針數組，存放節點i所指向的節點的指針  tot爲邊數組的下標
int n;
bool vist[maxn];

void addedge(int a, int b, int c)  // 添加從a指向b的邊，權值爲c
{
    edge[tot].v = b, edge[tot].next = eh[a], edge[tot].cost = c;
    eh[a] = tot++;
}

void dij(int s)  // 以s爲起點求最短路
{
    for (int i = 0; i <= n; i++) dist[i] = inf, vist[i] = false;
    dist[s] = 0;
    priority_queue< Edge > que;
    que.push(Edge(s, 0));
    while (!que.empty()) {
        int u = que.top().v;
        que.pop();
        if (vist[u]) continue;
        vist[u] = true;
        for (int j = eh[u]; j != -1; j = edge[j].next) {
            int v = edge[j].v;
            if (!vist[v] && dist[u] + edge[j].cost < dist[v]) {
                dist[v] = dist[u] + edge[j].cost;
                que.push(Edge(v, dist[v]));
            }
        }
    }
}

void init()  // 初始化
{
    tot = 0;
    memset(eh, -1, sizeof (eh));
}

int main()
{
    freopen("in", "r", stdin);
    int m, a, b, c;
    while(scanf("%d%d", &n, &m), n||m) {
        init();
        for(int i = 0; i < m; i++) {
            scanf("%d%d%d", &a, &b, &c);
            addedge(a, b, c);
            addedge(b, a, c);
        }
        dij(1);
        printf("%d\n", dist[n]);
    }
    return 0;
}