c++拾趣——vector添加元素引发的问题

  1 /*
  2  * Problem:  
  3  * Author:  SHJWUDP
  4  * Created Time:  2015/10/10 星期六 22:05:21
  5  * File Name: 1001.cpp
  6  * State: 
  7  * Memo: 
  8  */
  9 #include <iostream>
 10 #include <cstdio>
 11 #include <vector>
 12 #include <cstring>
 13 #include <algorithm>
 14 
 15 using namespace std;
 16 
 17 struct Graph {
 18     struct Edge {
 19         int u, v, w;
 20         Edge(int _u, int _v, int _w):u(_u),v(_v),w(_w){}
 21     };
 22     int n, m;
 23     vector<Edge> edges;
 24     vector<vector<int> > G;
 25     vector<int> pw;
 26     Graph(int _n):n(_n),m(0),G(_n),pw(_n){}
 27     void addEdge(int u, int v, int w) {
 28         edges.push_back(Edge(u,v,w));
 29         m=edges.size();
 30         G[u].push_back(m-1);
 31     }
 32     vector<int> & operator[](int x) {
 33         return G[x];
 34     }
 35 };
 36 
 37 struct Trie {
 38     struct Node {
 39         static const int SIGMA=2;
 40         vector<int> ch;
 41         Node():ch(SIGMA, -1){}
 42     };
 43     vector<Node> tree;
 44     Trie():tree(1){}
 45     int newNode() {
 46         tree.push_back(Node());
 47         return tree.size()-1;
 48     }
 49     void insert(int x) {
 50         int p=0;
 51         for(int k=30; k>=0; --k) {
 52             int & nt=tree[p].ch[!!(x & (1<<k))];
 53             if(nt==-1) nt=newNode();
 54             p=nt;
 55         }
 56     }
 57     int query(int x) {
 58         int ret=0;
 59         int p=0;
 60         for(int k=30; k>=0; --k) {
 61             int tmp=!!(x&(1<<k));
 62             if(tree[p].ch[!tmp]!=-1) {
 63                 ret|=1<<k;
 64                 p=tree[p].ch[!tmp];
 65             } else if(tree[p].ch[tmp]!=-1) {
 66                 p=tree[p].ch[tmp];
 67             }
 68         }
 69         return ret;
 70     }
 71 };
 72 
 73 int n;
 74 void dfs(Graph & G, int u, int fa, int val) {
 75     G.pw[u]=val;
 76     for(int i=0; i<(int)G[u].size(); ++i) {
 77         const Graph::Edge & e=G.edges[G[u][i]];
 78         if(e.v==fa) continue;
 79         dfs(G, e.v, u, val^e.w);
 80     }
 81 }
 82 int main() {
 83 #ifndef ONLINE_JUDGE
 84     freopen("in", "r", stdin);
 85 //    freopen("out", "w", stdout);
 86 #endif
 87     while(~scanf("%d", &n)) {
 88         Graph tree(n);
 89         for(int i=0; i<n-1; ++i) {
 90             int a, b, c;
 91             scanf("%d%d%d", &a, &b, &c);
 92             tree.addEdge(a, b, c);
 93             tree.addEdge(b, a, c);
 94         }
 95         dfs(tree, 0, -1, 0);
 96         Trie trie;
 97         for(int i=0; i<n; ++i) {
 98             trie.insert(tree.pw[i]);
 99         }
100         int ans=0;
101         for(int i=0; i<n; ++i) {
102             ans=max(ans, trie.query(tree.pw[i]));
103         }
104         printf("%d\n", ans);
105     }
106     return 0;
107 }

  1 /*
  2  * Problem:
  3  * Author:  SHJWUDP
  4  * Created Time:  2015/10/10 星期六 22:05:21
  5  * File Name: 1001.cpp
  6  * State:
  7  * Memo:
  8  */
  9 #include <iostream>
 10 #include <cstdio>
 11 #include <vector>
 12 #include <cstring>
 13 #include <algorithm>
 14 
 15 using namespace std;
 16 
 17 struct Graph {
 18     struct Edge {
 19         int u, v, w;
 20         Edge(int _u, int _v, int _w):u(_u),v(_v),w(_w){}
 21     };
 22     int n, m;
 23     vector<Edge> edges;
 24     vector<vector<int> > G;
 25     vector<int> pw;
 26     Graph(int _n):n(_n),m(0),G(_n),pw(_n){}
 27     void addEdge(int u, int v, int w) {
 28         edges.push_back(Edge(u,v,w));
 29         m=edges.size();
 30         G[u].push_back(m-1);
 31     }
 32     vector<int> & operator[](int x) {
 33         return G[x];
 34     }
 35 };
 36 
 37 struct Trie {
 38     struct Node {
 39         static const int SIGMA=2;
 40         vector<int> ch;
 41         Node():ch(SIGMA, -1){}
 42     };
 43     vector<Node> tree;
 44     Trie():tree(1){}
 45     int newNode() {
 46         tree.push_back(Node());
 47         return tree.size()-1;
 48     }
 49     int next(int & x) {
 50         int ret=x;
 51         if(x==-1) {
 52             ret=x=tree.size();
 53             tree.push_back(Node());
 54         }
 55         return ret;
 56     }
 57     void insert(int x) {
 58         int p=0;
 59         for(int k=30; k>=0; --k) {
 60             p=next(tree[p].ch[!!(x&(1<<k))]);
 61         }
 62     }
 63     int query(int x) {
 64         int ret=0;
 65         int p=0;
 66         for(int k=30; k>=0; --k) {
 67             int tmp=!!(x&(1<<k));
 68             if(tree[p].ch[!tmp]!=-1) {
 69                 ret|=1<<k;
 70                 p=tree[p].ch[!tmp];
 71             } else if(tree[p].ch[tmp]!=-1) {
 72                 p=tree[p].ch[tmp];
 73             }
 74         }
 75         return ret;
 76     }
 77 };
 78 
 79 int n;
 80 void dfs(Graph & G, int u, int fa, int val) {
 81     G.pw[u]=val;
 82     for(int i=0; i<(int)G[u].size(); ++i) {
 83         const Graph::Edge & e=G.edges[G[u][i]];
 84         if(e.v==fa) continue;
 85         dfs(G, e.v, u, val^e.w);
 86     }
 87 }
 88 int main() {
 89 #ifndef ONLINE_JUDGE
 90     freopen("in", "r", stdin);
 91 //    freopen("out", "w", stdout);
 92 #endif
 93     while(~scanf("%d", &n)) {
 94         Graph tree(n);
 95         for(int i=0; i<n-1; ++i) {
 96             int a, b, c;
 97             scanf("%d%d%d", &a, &b, &c);
 98             tree.addEdge(a, b, c);
 99             tree.addEdge(b, a, c);
100         }
101         dfs(tree, 0, -1, 0);
102         Trie trie;
103         for(int i=0; i<n; ++i) {
104             trie.insert(tree.pw[i]);
105         }
106         int ans=0;
107         for(int i=0; i<n; ++i) {
108             ans=max(ans, trie.query(tree.pw[i]));
109         }
110         printf("%d\n", ans);
111     }
112     return 0;
113 }