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add permutations_ii.c and re-implement permutations_i.c (#868)

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Yudong Jin 2023-10-17 10:20:10 -05:00 committed by GitHub
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3 changed files with 126 additions and 47 deletions
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1
codes/c/chapter_backtracking/CMakeLists.txt
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@ -1,4 +1,5 @@
add_executable(permutations_i permutations_i.c)
add_executable(permutations_ii permutations_ii.c)
add_executable(preorder_traversal_i_compact preorder_traversal_i_compact.c)
add_executable(preorder_traversal_ii_compact preorder_traversal_ii_compact.c)
add_executable(preorder_traversal_iii_compact preorder_traversal_iii_compact.c)

87
codes/c/chapter_backtracking/permutations_i.c
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@ -1,82 +1,79 @@
/**
* File: permutations_i.c
* Created Time: 2023-06-04
* Author: Gonglja (glj0@outlook.com)
* Author: Gonglja (glj0@outlook.com), Krahets (krahets@163.com)
*/
#include "../utils/common.h"
// 假设最多有 1000 个排列
#define MAX_SIZE 1000
/* 回溯算法：全排列 I */
void backtrack(vector *state, vector *choices, vector *selected, vector *res) {
void backtrack(int *state, int stateSize, int *choices, int choicesSize, bool *selected, int **res, int *resSize) {
// 当状态长度等于元素数量时，记录解
if (state->size == choices->size) {
vector *newState = newVector();
for (int i = 0; i < state->size; i++) {
vectorPushback(newState, state->data[i], sizeof(int));
if (stateSize == choicesSize) {
res[*resSize] = (int *)malloc(choicesSize * sizeof(int));
for (int i = 0; i < choicesSize; i++) {
res[*resSize][i] = state[i];
}
vectorPushback(res, newState, sizeof(vector));
(*resSize)++;
return;
}
// 遍历所有选择
for (int i = 0; i < choices->size; i++) {
int *choice = malloc(sizeof(int));
*choice = *((int *)(choices->data[i]));
// 剪枝：不允许重复选择元素 且 不允许重复选择相等元素
bool select = *((bool *)(selected->data[i]));
if (!select) {
for (int i = 0; i < choicesSize; i++) {
int choice = choices[i];
// 剪枝：不允许重复选择元素
if (!selected[i]) {
// 尝试：做出选择，更新状态
*((bool *)selected->data[i]) = true;
vectorPushback(state, choice, sizeof(int));
selected[i] = true;
state[stateSize] = choice;
// 进行下一轮选择
backtrack(state, choices, selected, res);
backtrack(state, stateSize + 1, choices, choicesSize, selected, res, resSize);
// 回退：撤销选择，恢复到之前的状态
*((bool *)selected->data[i]) = false;
vectorPopback(state);
selected[i] = false;
}
}
}
/* 全排列 I */
vector *permutationsI(vector *nums) {
vector *iState = newVector();
int select[3] = {false, false, false};
vector *bSelected = newVector();
for (int i = 0; i < nums->size; i++) {
vectorPushback(bSelected, &select[i], sizeof(int));
int **permutationsI(int *nums, int numsSize, int *returnSize) {
int *state = (int *)malloc(numsSize * sizeof(int));
bool *selected = (bool *)malloc(numsSize * sizeof(bool));
for (int i = 0; i < numsSize; i++) {
selected[i] = false;
}
int **res = (int **)malloc(MAX_SIZE * sizeof(int *));
*returnSize = 0;
vector *res = newVector();
backtrack(state, 0, nums, numsSize, selected, res, returnSize);
free(state);
free(selected);
// 前序遍历
backtrack(iState, nums, bSelected, res);
return res;
}
/* 打印向量中的元素 */
void printFunc(vector *v, void *p) {
int *node = p;
printf("%d", *node);
}
/* Driver Code */
int main() {
int nums[] = {1, 2, 3};
vector *iNums = newVector(); // int
for (int i = 0; i < sizeof(nums) / sizeof(nums[0]); i++) {
vectorPushback(iNums, &nums[i], sizeof(int));
}
int numsSize = sizeof(nums) / sizeof(nums[0]);
int returnSize;
vector *res = permutationsI(iNums);
int **res = permutationsI(nums, numsSize, &returnSize);
// 输出结果
printf("输入数组 nums = ");
printArray(nums, sizeof(nums) / sizeof(nums[0]));
printf("所有排列 res = ");
printVectorMatrix(res, printFunc);
printArray(nums, numsSize);
printf("\n所有排列 res = \n");
for (int i = 0; i < returnSize; i++) {
printArray(res[i], numsSize);
}
// 释放内存
delVector(iNums);
delVector(res);
for (int i = 0; i < returnSize; i++) {
free(res[i]);
}
free(res);
return 0;
}

81
codes/c/chapter_backtracking/permutations_ii.c Normal file
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/**
* File: permutations_ii.c
* Created Time: 2023-10-17
* Author: Krahets (krahets@163.com)
*/
#include "../utils/common.h"
// 假设最多有 1000 个排列，元素最大为 1000
#define MAX_SIZE 1000
/* 回溯算法：全排列 II */
void backtrack(int *state, int stateSize, int *choices, int choicesSize, bool *selected, int **res, int *resSize) {
// 当状态长度等于元素数量时，记录解
if (stateSize == choicesSize) {
res[*resSize] = (int *)malloc(choicesSize * sizeof(int));
for (int i = 0; i < choicesSize; i++) {
res[*resSize][i] = state[i];
}
(*resSize)++;
return;
}
// 遍历所有选择
bool duplicated[MAX_SIZE] = {false};
for (int i = 0; i < choicesSize; i++) {
int choice = choices[i];
// 剪枝：不允许重复选择元素 且 不允许重复选择相等元素
if (!selected[i] && !duplicated[choice]) {
// 尝试：做出选择，更新状态
duplicated[choice] = true; // 记录选择过的元素值
selected[i] = true;
state[stateSize] = choice;
// 进行下一轮选择
backtrack(state, stateSize + 1, choices, choicesSize, selected, res, resSize);
// 回退：撤销选择，恢复到之前的状态
selected[i] = false;
}
}
}
/* 全排列 II */
int **permutationsII(int *nums, int numsSize, int *returnSize) {
int *state = (int *)malloc(numsSize * sizeof(int));
bool *selected = (bool *)malloc(numsSize * sizeof(bool));
for (int i = 0; i < numsSize; i++) {
selected[i] = false;
}
int **res = (int **)malloc(MAX_SIZE * sizeof(int *));
*returnSize = 0;
backtrack(state, 0, nums, numsSize, selected, res, returnSize);
free(state);
free(selected);
return res;
}
/* Driver Code */
int main() {
int nums[] = {1, 1, 2};
int numsSize = sizeof(nums) / sizeof(nums[0]);
int returnSize;
int **res = permutationsII(nums, numsSize, &returnSize);
printf("输入数组 nums = ");
printArray(nums, numsSize);
printf("\n所有排列 res = \n");
for (int i = 0; i < returnSize; i++) {
printArray(res[i], numsSize);
}
// 释放内存
for (int i = 0; i < returnSize; i++) {
free(res[i]);
}
free(res);
return 0;
}