haha

Author: Jie Feng

codeforces/438C.cpp

@@ -981,18 +981,34 @@ int n;
 #define nn(x) (x>=n?x-n:x)
 const ll mod =  1000000007;
 
-typedef  point pt;
-typedef double ld;
 
-inline bool between(pt a, pt b, pt c)
+inline bool between(point a, point b, point c)
 {
-	ld aa = atan2(a.y, a.x);
-	ld ab = atan2(b.y, b.x);
-	ld ac = atan2(c.y, c.x);
+	double aa = atan2(a.y, a.x);
+	double ab = atan2(b.y, b.x);
+	double ac = atan2(c.y, c.x);
 	while (ab < aa) ab += 2 * 3.14159265358;
 	while (ac < aa) ac += 2 * 3.14159265358;
 	return ac < ab;
 }
+
+bool inside_polygon(int j1, int j2, int n, point p[], double area){
+//    assert(j1 < j2);
+/* 	double area = 0;
+ * 	for (int i = 0; i < n; i++) area += p[i] * p[i + 1];
+ * 	if (area < 0){
+ * 		reverse(p, p + n);
+ *         area = -area;
+ * 	}
+ *     p[n] = p[0];
+ */
+
+    double sq = 0;
+	for (int i = 0; i < j1; i++) sq += p[i] * p[i + 1];
+    sq += p[j1] * p[j2];
+	for (int i = j2; i < n; i++) sq += p[i] * p[i + 1];
+    return 0 <= sq && sq <= area;
+}
 int main(){
     scanf("%d", &n);
     clr(can, true);
@@ -1008,24 +1024,17 @@ int main(){
 	{
 		reverse(p, p + n);
 		p[n] = p[0];
+        sq = -sq;
 	}
 
-    if (p[0].x == -744281){
-        cout << 144076085 << endl;
-        return 0;
-    }
-
-    if (p[0].x == -62958){
-        cout << 589057227 << endl;
-        return 0;
-    }
 
 
     F(i,0,n)
         F(j,i+2,n){
             if (i == 0 && j == n-1) continue;
 //            if (!inside_polygon(p[j], p[i], n, p)){
-			if (!between(p[j + 1] - p[j], p[j - 1] - p[j], p[i] - p[j])) {
+            if (!inside_polygon(i, j, n, p, sq)){
+//			if (!between(p[j + 1] - p[j], p[j - 1] - p[j], p[i] - p[j])) {
 //                cout << i << ' ' << j << endl;
                 can[i][j] = can[j][i] = false;
                 continue;

codeforces/in

@@ -1,5 +1,6 @@
-4
-0 0
-0 1
-1 1
-1 0
+5
+0 0
+1 0
+1 1
+0 1
+-2 -1

interview/convert-BST-to-doublelinkedlist.cpp

@@ -1,3 +1,6 @@
+/* Facebook
+ * http://www.mitbbs.com/article_t/JobHunting/32705761.html
+ */
 #include<iostream>
 
 using namespace std;

interview/convert-string-to-words-array

@@ -0,0 +1,13 @@
+//http://www.mitbbs.com/article_t/JobHunting/32709291.html
+#include<iostream>
+#include<string>
+#include<vector>
+using namespace std;
+
+
+vector<string> convert_string_to_words(string s){
+
+
+}
+int main(){
+}

interview/copy-list-with-random-pointer.cpp

@@ -0,0 +1,22 @@
+//http://www.mitbbs.com/article_t/JobHunting/32708493.html
+/**
+ * Definition for singly-linked list with a random pointer.
+ * struct RandomListNode {
+ *     int label;
+ *     RandomListNode *next, *random;
+ *     RandomListNode(int x) : label(x), next(NULL), random(NULL) {}
+ * };
+ */
+class Solution {
+private:
+    map<RandomListNode*, RandomListNode*> mRR;
+public:
+    RandomListNode *copyRandomList(RandomListNode *head) {
+        if (head == NULL) return NULL;
+        RandomListNode* cur = new RandomListNode(head->label);
+        mRR[head] = cur;
+        cur->next = copyRandomList(head->next);
+        cur->random = mRR[head->random];
+        return cur;
+    }
+};

interview/count-inversions.cpp

@@ -0,0 +1,51 @@
+/*
+ * http://www.mitbbs.com/article_t/JobHunting/32708791.html
+ */
+#include<iostream>
+#include<cstring>
+#include<vector>
+using namespace std;
+
+
+
+int merge(int A[], int L, int M, int R){
+    int *B = new int[R-L+1];
+    int L1 = L, L2 = M+1, i = 0;
+    int cnt = 0;
+    while(L1 <= M && L2 <= R){
+        if (A[L1] <= A[L2]){
+            B[i++] = A[L1++];
+            cnt += L2-(M+1);
+        }else
+            B[i++] = A[L2++];
+    }
+
+    if (L1 <= M){
+        cnt += (M+1-L1) * (R-M);
+        while(L1 <= M){
+            B[i++] = A[L1++];
+        }
+    }else{
+        while(L2 <= R){
+            B[i++] = A[L2++];
+        }
+    }
+
+    memcpy(A+L, B, sizeof(int)*(R-L+1));
+    return cnt;
+}
+
+int count(int A[], int L, int R){
+    if (L == R) return 0;
+    int M = (L + R) / 2;
+    int cnt = count(A, L, M) + count(A, M+1, R);
+//    cout << L << ' ' << R << ' ' << cnt << endl;
+    cnt += merge(A, L, M, R);
+    return cnt;
+}
+
+int main(){
+    int A[] = {5,4,3,2,1};
+    int n = sizeof(A)/4;
+    cout << count(A, 0, n-1) << endl;
+}

interview/count-numbers-contain-5

@@ -0,0 +1,55 @@
+/*
+ * http://www.mitbbs.com/article_t/JobHunting/32710149.html
+ *
+给任意一个数N，求小于N的数里含数字5的个数。
+比如26，小于26的数有5，15，25含有5，所以返回3。
+这题看起来挺简单，可是给跪了。。。。。
+ */
+#include<iostream>
+#include<vector>
+using namespace std;
+
+int count_numbers_contain(int n, int b){
+    if (n <= 0) return 0;
+    vector<int> bits;
+    while(n != 0){
+        bits.push_back(n % 10);
+        n /= 10;
+    }
+    vector<int> ten(bits.size()+1);
+
+    vector<int> F(bits.size()+1);
+
+    //F[i] = count of numbers of i+1 digits which contanis specific bit 
+
+    F[0] = 0;
+    ten[0] = 1;
+    for (int i = 1; i < bits.size(); i++){
+        ten[i] = ten[i-1] * 10;
+        F[i] = F[i-1] * 9 + ten[i-1];
+    }
+
+    int cnt = 0;
+    for (int i = bits.size()-1; i >= 0; i--){
+
+
+        if (b < bits[i]){
+            cnt += ten[i];
+            cnt += (bits[i]-1) * F[i];
+        }else cnt += bits[i] * F[i];
+
+        if (bits[i] == b && i != 0){
+            cnt += n % ten[i-1];
+            break;
+        }
+    }
+    if (b == 0){
+        for (int i = bits.size()-1; i >= 1; i--){
+            cnt -= 9 * ten[i-1];
+        }
+    }
+    return cnt;
+}
+int main(){
+    cout << count_numbers_contain(23, 0) << endl;
+}

interview/count-numbers-contain-5.cpp

@@ -0,0 +1,70 @@
+/*
+ * given 一个字符串，这个字符串是一个算式，包含加减乘除，没有括号，符号和数
+字之间以一个空格格开，比如：“1 + 2 * 4 / 5”，return算式的结果
+ */
+#include<iostream>
+#include<string>
+#include<stack>
+#include<sstream>
+using namespace std;
+
+int expression(string exp){
+    stringstream ss(exp);
+    char c, op;
+
+    stack<int> nums;
+    stack<char> ops;
+
+    int num, num1;
+
+    while(true){
+//        cout << "New round ....." << endl;
+        while(!ss.eof() && ss.peek() == ' '){
+//            cout << ss.peek() << " ";
+            ss.get(c);
+//            cout << (int)c << endl;
+        }
+
+        if (ss.eof()) break;
+        c = ss.peek();
+
+        if ('0' <= c && c <= '9'){
+            ss >> num;
+            if (!ops.empty()){ 
+                op = ops.top();
+                if (op == '*' || op == '/'){
+                    ops.pop();
+                    num1 = nums.top(); nums.pop();
+                    if (op == '*'){
+                        num = num1 * num;
+                    }else{
+                        num = num1 / num;
+                    }
+                }
+            } 
+            nums.push(num);
+        }else{
+            ss >> op;
+            ops.push(c);
+        }
+    }
+    while(!ops.empty()){
+        num = nums.top(); nums.pop();
+        num1 = nums.top(); nums.pop();
+        op = ops.top(); ops.pop();
+        if (op == '+'){
+            nums.push(num1+num);
+        }else{
+            nums.push(num1-num);
+        }
+    }
+    return nums.top();
+
+
+}
+
+
+int main(){
+    cout << expression("1 + 2 * 4 * 5") << endl;
+}
+