void merge(int *A, int q, int mid, int r) {
int i, j, k;
int lnum = mid - q + 1;
int rnum = r - mid;
int *L = (int *)malloc(sizeof(int)*(lnum + 1));
int *R = (int *)malloc(sizeof(int)*(rnum + 1));
for (i = 0; i < lnum; i++) {
L[i] = A[q + i];
}
L[i] = INT_MAX;
for (i = 0; i < rnum; i++) {
R[i] = A[mid + i + 1];
}
R[i] = INT_MAX;
i = 0;
j = 0; //用不同的符号推进三个数组
k = 0;
while (k < (lnum + rnum)) {
if (L[j] > R[i]) {
A[q + k] = R[i];
i++;
} else {
A[q + k] = L[j];
j++;
}
k++;
}
free(L);
free(R);
L = NULL;
R = NULL;
}
void mergesort(int *A, int q, int r) {
if (q < r) {
int mid = (q + r) / 2;
mergesort(A, q, mid);
mergesort(A, mid + 1, r);
merge(A, q, mid, r);
}
}
void split(int *A, int q, int r, int *k) {
int i, j;
int x, temp;
i = q;
x = A[q];
for (j = q + 1; j <= r; j++) {
if (A[j] <= x) {
i = i + 1;
if (i != j) { //此处i指向第一个比x大的值
temp = A[j];
A[j] = A[i];
A[i] = temp;
}
}
}
temp = A[i]; //此处i指向最后一个比x小的值
A[i] = A[q];
A[q] = temp;
*k = i;
}
void quicksort(int *A, int q, int r) {
int k;
if (q < r) {
split(A, q, r, &k);
quicksort(A, q, k - 1); //注意这里是k-1,因为是原址排序,上面第k个的位置已经是正确的了
quicksort(A, k + 1, r);
}
}
void insertsort(int *A, int num) {
int i, j;
int temp;
for (i = 1; i < num; i++) {
temp = A[i];
for (j = i - 1; j >= 0; j--) {
if (temp > A[j]) { //大于其中一个,前面的肯定比它大
break;
}
else {
A[j + 1] = A[j];
}
}
A[j + 1] = temp;
}
}
void selectsort(int *A, int num) {
int i, j;
int temp;
for (i = 0; i < num - 1; i++) { //查找第i小元素
for (j = i + 1; j < num; j++) {
if (A[i] > A[j]) {
temp = A[i];
A[i] = A[j];
A[j] = temp;
}
}
}
}
void bubblesort(int *A, int num) {
int i, j;
int temp;
for (i = 0; i < num - 1; i++) { //运行次数
for (j = 0; j < num - i - 1; j++) {
if (A[j] > A[j + 1]) {
temp = A[j];
A[j] = A[j + 1];
A[j + 1] = temp;
}
}
}
}
常见的排序算法C语言实现(—)
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转载自blog.csdn.net/xtydtc/article/details/77016616
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