hdu1384查分约束（最短路径）

#include <iostream>#include <cstdio>#include <cstring>#include <queue>using namespace std;const int MAX = 0x7FFFFFFF;const int M = 500005;int head[M];struct node {    int to;    int value;    int next;}edge[M];int n;int dist[M];int vist[M];int cnt;int maxn, minn;void init() {       cnt = 0;        maxn = -MAX;        minn = MAX;    memset(head, -1, sizeof(head));  //  memset(dist, MAX, sizeof(dist));    memset(vist, 0, sizeof(vist));}void add(int v, int u, int d) {    edge[cnt].to = u;    edge[cnt].value = d;    edge[cnt].next = head[v];    head[v] = cnt++;}void SPFA(int u) {    for(int i = 0; i <= maxn; i++) {        dist[i] = -500000;    }    queue<int>que;    while(!que.empty()) que.pop();    dist[u] = 0;    vist[u] = 1;    que.push(u);    while(!que.empty()) {        u = que.front();        que.pop();        vist[u] = 0;        for(int k = head[u]; k != -1; k = edge[k].next) {            int v = edge[k].to;            int d = edge[k].value;            if(dist[v] < dist[u] + d) {             // printf("%d  %d   %d  %d\n", v, u, dist[v], dist[u]);                dist[v] = dist[u] + d;                if(vist[v] == 0)                {                    vist[v] = 1;                   que.push(v);                }            }        }    }    printf("%d\n", dist[maxn]);}int main(){    int x, y, d;    while(scanf("%d", &n) != EOF) {        init();        for(int i = 1; i <= n; i++) {            scanf("%d%d%d", &x, &y, &d);            minn = min(minn, x);            maxn = max(y + 1, maxn);            add(x, y+1, d);        }        for(int i = minn; i <= maxn; i++)        {            add(i, i+1, 0);            add(i+1, i, -1);        }        SPFA(minn);    }    return 0;}