add

10.6.1.cpp

@@ -0,0 +1,78 @@
+#include <iostream>
+#include <map>
+#include <cmath>
+#include <cstdlib>
+#include <ctime>
+using namespace std;
+
+struct point{
+    double x, y;
+};
+class line{
+public:
+    double epsilon, slope, intercept;
+    bool bslope;
+public:
+    line(){}
+    line(point p, point q){
+        epsilon = 0.0001;
+        if(abs(p.x - q.x) > epsilon){
+            slope = (p.y-q.y) / (p.x-q.x);
+            intercept = p.y - slope * p.x;
+            bslope = true;
+        }
+        else{
+            bslope = false;
+            intercept = p.x;
+        }
+    }
+    int hashcode(){
+        int sl = (int)(slope * 1000);
+        int in = (int)(intercept * 1000);
+        return sl*1000 +  in;
+    }
+    void print(){
+        cout<<"y = "<<slope<<"x + "<<intercept<<endl;
+    }
+};
+
+line find_best_line(point *p, int point_num){
+    line bestline;
+    bool first = true;
+    map<int, int> mii;
+    for(int i=0; i<point_num; ++i){
+        for(int j=i+1; j<point_num; ++j){
+            line l(p[i], p[j]);
+            if(mii.find(l.hashcode()) == mii.end()){
+                mii[l.hashcode()] = 0;
+            }
+            mii[l.hashcode()] = mii[l.hashcode()] + 1;
+            if(first){
+                bestline = l;
+                first = false;
+            }
+            else{
+                if(mii[l.hashcode()] > mii[bestline.hashcode()])
+                    bestline = l;
+            }
+        }
+    }
+    // int a = mii[bestline.hashcode()];
+    // cout<<mii[bestline.hashcode()]<<endl;
+    // cout<<(1+sqrt(1+8*a))/2<<endl;
+    return bestline;
+}
+int main(){
+    srand((unsigned)time(0));
+    int graph_size = 100;
+    int point_num = 500;
+    point *p = new point[point_num];
+    for(int i=0; i<point_num; ++i){
+        p[i].x = rand()/double(RAND_MAX) * graph_size;
+        p[i].y = rand()/double(RAND_MAX) * graph_size;
+        //cout<<p[i].x<<" "<<p[i].y<<endl;
+    }
+    line l = find_best_line(p, point_num);
+    l.print();
+    return 0;
+}

10.7.cpp

@@ -0,0 +1,44 @@
+#include <iostream>
+#include <queue>
+using namespace std;
+
+int mini(int a, int b){
+    return a < b ? a : b;
+}
+int mini(int a, int b, int c){
+    return mini(mini(a, b), c);
+}
+int get_num(int k){
+    if(k <= 0) return 0;
+    int res = 1, cnt = 1;
+    queue<int> q3, q5, q7;
+    q3.push(3); q5.push(5); q7.push(7);
+    for(; cnt<k; ++cnt){
+        int v3 = q3.front();
+        int v5 = q5.front();
+        int v7 = q7.front();
+        res = mini(v3, v5, v7);
+        if(res == v7){
+            q7.pop();
+        }
+        else{
+            if(res == v5){
+                q5.pop();
+            }
+            else{
+                if(res == v3){
+                    q3.pop();
+                    q3.push(3*res);
+                }
+            }
+            q5.push(5*res);
+        }
+        q7.push(7*res);
+    }
+    return res;
+}
+int main(){
+    for(int i=1; i<20; ++i)
+        cout<<get_num(i)<<endl;
+    return 0;
+}

9.3.cpp

@@ -1,7 +1,6 @@
 #include <iostream>
 using namespace std;
 
-int cnt = 0;
 int search(int a[], int low, int high, int x){
     while(low <= high){
         //cout<<low<<" "<<high<<endl;
@@ -37,6 +36,5 @@ int main(){
         2,2,2,2,2,2,2,2,3,2,2,2,2,2,2,2,2,2,2
     };
     cout<<search(a, 0, 11, 3)<<endl;
-    cout<<cnt<<endl;
     return 0;
 }