Lintcode - 整数排序

class Solution {
public:
/*
* @param A: an integer array
* @return:
*/
void sortIntegers(vector<int> &A) {
// write your code here
//SelectionSort(A);
//bubleSort(A);
//selectionSort1(A);
//insertionSort(A);
ComparisonCountingSort(A);
}

private:
/*==================Selection sort======================*/
void SelectionSort(vector<int> &a) {
int n = a.size();
for (int i=0; i<n-1; i++) { // 当前从i=0,1,2...开始
int min = i;// 找到从i到末尾的最小元素，和i(也就是第一个元素交换)
for (int j=i+1; j<n; j++) {
if (a[j] < a[min])
min = j;
}
swap(a[i], a[min]);
}
}

/*==================buble sort=========================*/
void bubleSort(vector<int> &a) {
int n = a.size();

for (int i = 0; i < n-1; i++) { // a[i]和a[i                //+1]比较，范围到倒数第二个元素
for (int j = 0; j < n - 1 - i; j++) {  // 末尾减去i个已经排列好的
if (a[j] > a[j+1]) {
swap(a[j], a[j+1]);
}
}
}
}

/*==================Insertion Sort=====================*/
void insertionSort(vector<int> &a) {
int n = a.size();

for (int i=1; i<n; i++) { // 开始默认0元素已经排序好
int v = a[i];
int j = i-1;
while (j>=0 && a[j]>v) {
a[j+1] = a[j]; // 后移
j--;
}
a[j+1] = v;
}
}

/*==================Selection Sort递归方式=====================*/
int findSmallest(vector<int> &a, int start, int end) {
int min = start;
for (int i = start + 1; i <= end; i++) {
if (a[i] < a[min])
min = i;
}

return min;
}

void selectionSort1(vector<int> &a, int start, int end) {
if (start < end - 1) {
swap(a[start], a[findSmallest(a, start, end)]);
selectionSort1(a, start + 1, end);
}
}

void selectionSort1(vector<int> &a) {
if (a.size() <= 1)
return;

selectionSort1(a, 0, a.size() - 1);
}

/*===============ComparisonCountingSort======================*/
// 计数排序
void ComparisonCountingSort(vector<int> &a) {
int n = a.size();

int Count
;
for (int i=0; i<n; i++) {
Count[i] = 0;
}

for (int i=0; i<n-1; i++) {
for (int j=i+1; j<n; j++) {
if (a[i] < a[j]) {
Count[j] += 1;
} else {
Count[i] += 1;
}
}
}

vector<int> res;
res.resize(n);
for (int i=0; i<n; i++) {
res[Count[i]] = a[i];
}
a = res;
}
};