/*************************************************************************
> File Name: array.cpp
> Author: xinyang
> Mail: xuechen.xy@gmail.com
> Created Time: Tue 06 Oct 2015 03:14:34 PM CST
************************************************************************/
#include <iostream>
#include <algorithm>
#include <cstring>
#include <cstdio>
using namespace std;
/*
* 斐波那契数列
*/
int fibonacci(int n) {
if (n == 0 || n == 1) {
return n;
}
int a = 0, b = 1;
for (int i = 2; i <= n; ++i) {
int tmp = a + b;
a = b;
b = tmp;
}
return b;
}
/*
* 调整数组，将奇数放在所有偶数的前面
*/
void reorder_odd_even(int A[], int n) {
if (A == NULL || n <= 0) {
return;
}
int low = 0, high = n - 1;
while (low < high) {
while (low < high && (A[low] & 0x1) == 1) {
++low;
}
while (low < high && (A[high] & 0x1) == 0) {
--high;
}
if (low < high) {
int tmp = A[low];
A[low] = A[high];
A[high] = tmp;
}
}
}
/*
* 顺时针打印矩阵
*/
void print_matrix_in_circle(int A[][4], int columns, int rows, int start) {
int endX = columns - 1 - start;
int endY = rows - 1 - start;
for (int i = start; i <= endX; ++i) {
cout << A[start][i] << ' ';
}
if (start < endY) {
for (int i = start + 1; i <= endY; ++i) {
cout << A[i][endX] << ' ';
}
}
if (start < endX && start < endY) {
for (int i = endX - 1; i >= start; --i) {
cout << A[endY][i] << ' ';
}
}
if (start <= endX && start < endY - 1) {
for (int i = endY - 1; i >= start + 1; --i) {
cout << A[i][start] << ' ';
}
}
}
void print_matrix_clock_wisely(int A[][4], int columns, int rows) {
if (A == NULL || columns <= 0 || rows <= 0) {
return;
}
int start = 0;
while (columns > start * 2 && rows > start * 2) {
print_matrix_in_circle(A, columns, rows, start);
++start;
}
}
/*
* 数组中超过一半的数字
*/
int partition(int A[], int low, int high) {
int pivot = A[low];
while (low < high) {
while (low < high && A[high] >= pivot) {
--high;
}
A[low] = A[high];
while (low < high && A[low] <= pivot) {
++low;
}
A[high] = A[low];
}
A[low] = pivot;
return low;
}
bool check_more_than_half(int A[], int n, int result) {
int time = 0, half = n / 2;
for (int i = 0; i < n; ++i) {
if (A[i] == result) {
++ time;
if (time > half) {
return true;
}
}
}
return false;
}
int more_than_half_num1(int A[], int n) {
if (A == NULL || n <= 0) {
return -1;
}
int low = 0, high = n - 1, mid = (low + high) / 2;
int pivotpos = partition(A, low, high);
while (pivotpos != mid) {
if (pivotpos > mid) {
high = pivotpos - 1;
pivotpos = partition(A, low, high);
} else {
low = pivotpos + 1;
pivotpos = partition(A, low, high);
}
}
int result = A[mid];
if (!check_more_than_half(A, n, result)) {
result = -1;
}
return result;
}
int more_than_half_num2(int A[], int n) {
if (A == NULL || n <= 0) {
return 0;
}
int result = A[0];
int time = 1;
for (int i = 1; i < n; ++i) {
if (time == 0) {
result = A[i];
time = 1;
} else if (A[i] == result) {
++time;
} else {
--time;
}
}
if (!check_more_than_half(A, n, result)) {
result = -1;
}
return result;
}
/*
* 最小的k个数
*/
void get_least_k_num(int A[], int n, int output[], int k) {
if (A == NULL || k <= 0
|| output == NULL || k <= 0 || k > n) {
return;
}
int low = 0, high = n - 1;
int pivotpos = partition(A, low, high);
while (pivotpos != k - 1) {
if (pivotpos > k - 1) {
high = pivotpos - 1;
pivotpos = partition(A, low, high);
} else {
low = pivotpos + 1;
pivotpos = partition(A, low, high);
}
}
for (int i = 0; i < k; ++i) {
output[i] = A[i];
}
}
/*
* 连续字数组的最大和
*/
int get_greatest_continous_num(int A[], int n) {
if (A == NULL || n <= 0) {
return -1;
}
int cur_sum = 0;
int ret = 0x80000000;
for (int i = 0; i < n; ++i) {
if (cur_sum <= 0) {
cur_sum = A[i];
} else {
cur_sum += A[i];
}
if(cur_sum > ret) {
ret = cur_sum;
}
}
return ret;
}
/*
* 把数组排成最小的数
*/
char *combine_str1 = new char[100];
char *combine_str2 = new char[100];
int cmp(char *str1, char *str2) {
strcpy(combine_str1, str1);
strcat(combine_str1, str2);
strcpy(combine_str2, str2);
strcat(combine_str2, str1);
return strcmp(combine_str1, combine_str2);
}
void print_min_number(int A[], int n) {
if (A == NULL || n <= 0) {
return;
}
char **str_nums = (char **)(new int[n]);
for (int i = 0; i < n; ++i) {
str_nums[i] = new char[100];
sprintf(str_nums[i], "%d", A[i]);
}
sort(str_nums, str_nums + n, cmp);
for (int i = 0; i < n; ++i) {
cout << str_nums[i];
}
for (int i = 0; i < n; ++i) {
delete[] str_nums[i];
}
delete[] str_nums;
}
/*
* 获取排序数组中指定数字的个数
*/
int get_first_k(int A[], int n, int k, int low, int high) {
if (low > high) {
return -1;
}
int mid = (low + high) / 2;
int val_mid = A[mid];
if (val_mid == k) {
if ((mid > 0 && A[mid - 1] != k)
|| mid == 0) {
return mid;
} else {
high = mid - 1;
}
} else if (val_mid > k) {
high = mid - 1;
} else {
low = mid + 1;
}
return get_first_k(A, n, k, low, high);
}
int get_last_k(int A[], int n, int k, int low, int high) {
if (low > high) {
return -1;
}
int mid = (low + high) / 2;
int val_mid = A[mid];
if (val_mid == k) {
if ((mid < n - 1 && A[mid + 1] != k)
|| mid == n - 1) {
return mid;
} else {
low = mid + 1;
}
} else if (val_mid > k) {
high = mid - 1;
} else {
low = mid + 1;
}
return get_last_k(A, n, k, low, high);
}
int get_num_of_k(int A[], int n, int k) {
int num = 0;
if (A == NULL || n <= 0) {
return num;
}
int first = get_first_k(A, n, k, 0, n - 1);
int last = get_last_k(A, n, k, 0, n - 1);
if (first > -1 && last > -1) {
num = last - first + 1;
}
return num;
}
/*
* 和为s的两个数
*/
bool find_nums_with_sum(int A[], int n, int sum, int &num1, int &num2) {
if (A == NULL || n <= 0) {
return false;
}
int low = 0, high = n - 1;
while (low < high) {
long long cur_sum = A[low] + A[high];
if (cur_sum == sum) {
num1 = A[low];
num2 = A[high];
return true;
} else if (cur_sum > sum) {
--high;
} else {
++low;
}
}
return false;
}
/*
* 和为s的连续正数序列
*/
void print_sequence(int small, int big) {
for (int i = small; i <= big; ++i) {
cout << i << ' ';
}
}
void find_continuos_sequence(int sum) {
if (sum < 3) {
return;
}
int small = 1, big = 2;
int mid = (1 + sum) / 2;
int cur_sum = small + big;
while (small < mid) {
if (cur_sum == sum) {
print_sequence(small, big);
}
while (cur_sum > sum && small < mid) {
cur_sum -= small;
++small;
if (cur_sum == sum) {
print_sequence(small, big);
}
}
++big;
cur_sum += big;
}
}
/*
* 扑克牌顺子（癞子斗地主）
*/
bool is_continuos(int A[], int n) {
bool ret = false;
if (A == NULL || n <= 0) {
return ret;
}
sort(A, A + n);
int zero = 0, gap = 0;
for (int i = 0; i < n && A[i] == 0;
++i) {
++zero;
}
int small = zero, big = small + 1;
while (big < n) {
if (A[small] == A[big]) {
return ret;
}
gap += (A[big] - A[small] - 1);
small = big;
++big;
}
if (gap <= zero) {
ret = true;
}
return ret;
}
int main() {
cout << "fibonacci" << endl;
cout << fibonacci(5) << endl << endl;
cout << "reorder odd and even" << endl;
int A[] = {3, 8, 7, 1, 2, 5, 4, 6, 9};
reorder_odd_even(A, 9);
for (int i = 0; i < 9; ++i) {
cout << A[i] << ' ';
}
cout << endl << endl;
cout << "print a matrix clockwisely" << endl;
int B[][4] = {
1, 2, 8, 9,
2, 4, 9, 12,
4, 7, 10, 13,
6, 8, 11, 15};
print_matrix_clock_wisely(B, 4, 4);
cout << endl << endl;
cout << "more than half" << endl;
int C[] = {1, 2, 3, 1, 1};
// cout << more_than_half_num1(C, 5) << endl << endl;
cout << more_than_half_num2(C, 5) << endl << endl;
cout << "get least k numbers" << endl;
int output[5];
get_least_k_num(A, 9, output, 5);
for (int i = 0; i < 5; ++i) {
cout << output[i] << ' ';
}
cout << endl << endl;
cout << "get greatest continuos numbers" << endl;
cout << get_greatest_continous_num(A, 9) << endl << endl;
cout << "print minimum number" << endl;
int D[] = {3, 32, 321};
print_min_number(D, 3);
cout << endl <<endl;
cout << "get number of k" << endl;
int E[] = {1, 2, 3, 3, 3, 4, 5};
cout << get_num_of_k(E, 7, 3) << endl <<endl;;
cout << "find two numbers with their sum" << endl;
int num1, num2;
find_nums_with_sum(E, 7, 5, num1, num2);
cout << "number1: " << num1 << " number2: " << num2 << endl << endl;
cout << "find continuos sequence" << endl;
find_continuos_sequence(45);
cout << endl << endl;
int F[]= {0, 0, 1, 3, 4};
if (true == is_continuos(F, 5)) {
cout << "is continuos" << endl << endl;
} else {
cout << "is not continuos" << endl << endl;
}
return 0;
}
