收集到的小玩意儿

1.二维数组偏移量读入

int a[1003][1003];

scanf("%d",&a[i][j]);    =    scanf("%d",a[i]+j);

2.读取无用字符

  scanf("%*c%*c");

3.unique函数，用于去重。见www.cnblogs.com/hua-dong/p/7943983.html

收集到的小玩意儿

4.vector数组下标默认从零开始！！！

5.priority_queue的自定义使用（例如堆优化Dijkstra）https://www.cnblogs.com/cielosun/p/5654595.html

 1 //FROM : https://www.cnblogs.com/cielosun/p/5654595.html
 2 int cost[MAX_V][MAX_V];
 3 int d[MAX_V], V, s;
 4 //自定义优先队列less比较函数
 5 struct cmp
 6 {
 7     bool operator()(int &a, int &b) const
 8     {
 9         //因为优先出列判定为!cmp，所以反向定义实现最小值优先
10         return d[a] > d[b];
11     }
12 };
13 void Dijkstra()
14 {
15     std::priority_queue<int, std::vector<int>, cmp> pq;
16     pq.push(s);
17     d[s] = 0;
18     while (!pq.empty())
19     {
20         int tmp = pq.top();pq.pop();
21         for (int i = 0;i < V;++i)
22         {
23             if (d[i] > d[tmp] + cost[tmp][i])
24             {
25                 d[i] = d[tmp] + cost[tmp][i];
26                 pq.push(i);
27             }
28         }
29     }
30 }

dijkstra堆优化