板子

我测得的是这个东西在不开$O2$的情况下比$pair+priorit{y}_{q}ueue$快了将近$1/3$

#include<bits/stdc++.h>
#define mid (l + r >> 1)
#define lson rt << 1, l, mid
#define rson rt << 1 | 1, mid + 1, rusing namespace std;const int N1 = 1e5 + 10, N2 = 2e5 + 10;
const int INF = 0x3f3f3f3f;int head[N1], to[N2], nex[N2], value[N2], cnt;int dis[N1];int n, m, s;inline int read(){int x = 0,f=1;char ch = getchar();while(ch<'0'||ch>'9'){if(ch=='-')f=-1;ch=getchar();}while(ch<='9'&&ch>='0'){x=x*10+ch-'0';ch=getchar();}return x*f;
}struct point {int id, dis;point(int a = 0, int b = 0) : id(a), dis(b) {}
}a[N1 << 2];point minp(point a, point b) {if(a.dis < b.dis)   return a;return b;
}void build_tree(int rt, int l, int r) {if(l == r) {a[rt].id = l;a[rt].dis = INF;return ;}build_tree(lson);build_tree(rson);a[rt].dis = INF;a[rt].id = a[rt << 1].id;
}void update_tree(int rt, int l, int r, int dis, int x) {if(l == r) {a[rt].dis = x;return ;}if(dis <= mid)  update_tree(lson, dis, x);else            update_tree(rson, dis, x);a[rt] = minp(a[rt << 1], a[rt << 1 | 1]);
}void add(int x, int y, int w) {to[cnt] = y;nex[cnt] = head[x];value[cnt] = w;head[x] = cnt++;
}void print_tree(int rt, int l, int r) {printf("%d %d\n", rt, a[rt].id);if(l == r) {// printf("%d %d\n", a[rt].id, a[rt].dis);return ;}print_tree(lson);print_tree(rson);
}void Dijkstra() {memset(dis, 0x3f, sizeof dis);dis[s] = 0;// print_tree(1, 1, n);update_tree(1, 1, n, 1, 0);// puts("");// print_tree(1, 1, n);for(int cas = 1; cas < n; cas++) {// cout << 1 << endl;point temp = a[1];// printf("%d %d\n", temp.id, temp.dis);update_tree(1, 1, n, temp.id, INF);for(int i = head[temp.id]; ~i; i = nex[i]) {if(dis[to[i]] > dis[temp.id] + value[i]) {// cout << 1 << endl;dis[to[i]] = dis[temp.id] + value[i];update_tree(1, 1, n, to[i], dis[to[i]]);}}}for(int i = 1; i <= n; i++)printf("%d%c", dis[i], i == n ? '\n' : ' ');
}int main() {// freopen("in.txt", "r", stdin);int x, y, w;memset(head, -1, sizeof head);n = read(), m = read(), s = read();build_tree(1, 1, n);for(int i = 0; i < m; i++) {x = read(), y = read(), w = read();// scanf("%d %d %d", &x, &y, &w);add(x, y, w);}Dijkstra();return 0;
}