modified

Author: tmp-coder

discrete-optimization/coloring/_coursera

@@ -0,0 +1,8 @@
+wNBw6FwlEeaEFQ4KWsLmjw
+Graph Coloring
+fmYLC, ./data/gc_50_3, solver.py, Coloring Problem 1
+IkKpq, ./data/gc_70_7, solver.py, Coloring Problem 2
+pZOjO, ./data/gc_100_5, solver.py, Coloring Problem 3
+XDQ31, ./data/gc_250_9, solver.py, Coloring Problem 4
+w7hAO, ./data/gc_500_1, solver.py, Coloring Problem 5
+tthbm, ./data/gc_1000_5, solver.py, Coloring Problem 6

discrete-optimization/coloring/gc.cpp

@@ -0,0 +1,109 @@
+#include<bits/stdc++.h>
+using namespace std;
+
+#define ms(x,v) memset((x),(v),sizeof(x))
+
+typedef long long LL;
+
+struct Node{
+    int num,weight;
+
+    bool operator<(const Node& o)const{
+        return weight < o.weight;
+    }
+};
+
+struct BitSet{
+    LL * col;
+    const static int base = 64;
+    BitSet(int n){
+        col = new LL[(n+base-1)/base * base];
+    }
+    pair<int,int> pos(int idx){
+        int arr_idx = (idx + base -1)/base;
+        int bit = idx % base;
+        return make_pair(arr_idx,bit);
+    }
+    int get(int idx){
+        pair<int,int> p = pos(idx);
+        return (col[p.first]>>p.second) & 1;
+    }
+    void set(int idx){
+        pair<int,int> p = pos(idx);
+        col[p.first]|= 1LL << p.second;
+    }
+};
+int n,e;
+vector<vector<int> > G;
+int find_min_col(int v,const vector<int> & col){
+    BitSet c(n);
+    for(int i : G[v])
+        if(col[i]!= -1)c.set(col[i]);
+    for(int cc = 0 ; cc < n ; ++cc)
+        if(!c.get(cc))return cc;
+}
+
+int greedy_algorithm(vector<int> & col){
+    int r = rand()  % n;
+    for(int i=0 ; i < col.size() ; ++i)col[i] =-1;
+    col[r] =0;
+    priority_queue<Node> Q;
+    Q.push(Node{r,(int)G[r].size()});
+    
+    while(!Q.empty()){
+        Node now = Q.top();Q.pop();
+        for(auto v : G[now.num]){
+            if(col[v] ==-1){
+                col[v] = find_min_col(v,col);
+                Q.push(Node{v,(int)G[v].size()});
+            }
+        }
+    }
+    return (* max_element(col.begin(),col.end())) +1;
+    return 0;
+}
+
+void init(int n){
+    G.resize(n);
+}
+
+int solve(vector<int>&color){
+    init(n);
+    return greedy_algorithm(color);
+}
+
+int main(){
+    // ios::sync_with_stdio(0);
+    // cin.tie(0);
+    srand (time(NULL));
+
+    // cout << "test ok\n";
+    cin >> n >> e;
+    init(n);
+    for(int _ =0 ; _ < e ; ++_){
+        int u,v;
+        cin >> u >> v;
+        G[u].push_back(v);
+        G[v].push_back(u);
+    }
+
+    int times = 5;
+    int ans = n;
+    vector<int> col(n);
+    
+    vector<int> tmp(n);
+    while(times --){
+        int now_ans = solve(tmp);
+        if(ans > now_ans){
+            ans = now_ans;
+            col = tmp;
+        }
+    }
+
+    // int ans = solve();
+    cout << ans << " " << "0\n";
+    for(int i  : col)
+        cout << i << " ";
+    
+    return 0;
+}

discrete-optimization/coloring/handout.pdf

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+#!/usr/bin/python
+# -*- coding: utf-8 -*-
+
+import os
+import sys
+def solve_it(input_data):
+    # Modify this code to run your optimization algorithm
+
+    # parse the input
+    # print("creat tmp file")
+    tmp_file_name = 'tmp.data'
+    tmp_file = open(tmp_file_name, 'w')
+    tmp_file.write(input_data)
+    tmp_file.close()
+
+    sys.path.append('..')
+    import helper
+
+    ans =  helper.cpp_runner('gc.cpp',tmp_file_name)
+    os.remove(tmp_file_name)
+
+    return ans
+
+import sys
+
+sys.path.append('..')
+import helper
+if __name__ == '__main__':
+    import sys
+    if len(sys.argv) > 1:
+        file_location = sys.argv[1].strip()
+        # with open(file_location, 'r') as input_data_file:
+        #     input_data = input_data_file.read()
+        print(helper.cpp_runner('gc.cpp',file_location))
+    else:
+        print('This test requires an input file.  Please select one from the data directory. (i.e. python solver.py ./data/gc_4_1)')
+