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84 lines
2.3 KiB
84 lines
2.3 KiB
/**
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* File: subset_sum_ii.c
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* Created Time: 2023-07-29
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* Author: Gonglja (glj0@outlook.com)
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*/
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#include "../utils/common.h"
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#define MAX_SIZE 100
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#define MAX_RES_SIZE 100
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// 状态（子集）
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int state[MAX_SIZE];
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int stateSize = 0;
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// 结果列表（子集列表）
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int res[MAX_RES_SIZE][MAX_SIZE];
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int resColSizes[MAX_RES_SIZE];
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int resSize = 0;
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/* 回溯算法：子集和 II */
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void backtrack(int target, int *choices, int choicesSize, int start) {
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// 子集和等于 target 时，记录解
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if (target == 0) {
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for (int i = 0; i < stateSize; i++) {
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res[resSize][i] = state[i];
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}
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resColSizes[resSize++] = stateSize;
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return;
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}
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// 遍历所有选择
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// 剪枝二：从 start 开始遍历，避免生成重复子集
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// 剪枝三：从 start 开始遍历，避免重复选择同一元素
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for (int i = start; i < choicesSize; i++) {
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// 剪枝一：若子集和超过 target ，则直接跳过
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if (target - choices[i] < 0) {
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continue;
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}
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// 剪枝四：如果该元素与左边元素相等，说明该搜索分支重复，直接跳过
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if (i > start && choices[i] == choices[i - 1]) {
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continue;
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}
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// 尝试：做出选择，更新 target, start
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state[stateSize] = choices[i];
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stateSize++;
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// 进行下一轮选择
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backtrack(target - choices[i], choices, choicesSize, i + 1);
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// 回退：撤销选择，恢复到之前的状态
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stateSize--;
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}
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}
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/* 比较函数 */
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int cmp(const void *a, const void *b) {
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return (*(int *)a - *(int *)b);
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}
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/* 求解子集和 II */
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void subsetSumII(int *nums, int numsSize, int target) {
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// 对 nums 进行排序
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qsort(nums, numsSize, sizeof(int), cmp);
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// 开始回溯
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backtrack(target, nums, numsSize, 0);
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}
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/* Driver Code */
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int main() {
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int nums[] = {4, 4, 5};
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int numsSize = sizeof(nums) / sizeof(nums[0]);
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int target = 9;
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subsetSumII(nums, numsSize, target);
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printf("输入数组 nums = ");
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printArray(nums, numsSize);
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printf("target = %d\n", target);
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printf("所有和等于 %d 的子集 res = \n", target);
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for (int i = 0; i < resSize; ++i) {
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printArray(res[i], resColSizes[i]);
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}
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return 0;
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}
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