LeetCode 题解 46. 全排列

46. 全排列 - 力扣（Leetcode）

题解

思路：DFS

- 注意：力扣测试数据时不会将全局变量重置，要手动重置

int ptr_line = 0;
int mark[6];
void deep_find(int depth, int* nums, int** ans, int numsSize, int* temp, int size) {
    for (int i = 0; i < numsSize; i++) {
        if (!mark[i]) {
            temp[depth] = nums[i];
            mark[i] = true;
            if (depth < numsSize - 1)
                deep_find(depth + 1, nums, ans, numsSize, temp, size);
            else 
                memcpy(ans[ptr_line++], temp, sizeof(int) * numsSize);
            mark[i] = false;
        }
    }
}
int** permute(int* nums, int numsSize, int* returnSize, int** returnColumnSizes) {
    int size = 1;
    ptr_line = 0;//全局变量要重置
    for (int i = 2; i <= numsSize; i++)
        size *= i;
    *returnSize = size;
    *returnColumnSizes = (int*)malloc(sizeof(int) * size);
    int** ans = (int**)malloc(sizeof(int*) * size);
    int* temp = (int*)malloc(sizeof(int) * numsSize);
    for (int i = 0; i < size; i++) {
        (*returnColumnSizes)[i] = numsSize;
        ans[i] = (int*)malloc(sizeof(int) * numsSize);
    }
    deep_find(0, nums, ans, numsSize, temp, size);
    return ans;
}

测试函数

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
 
int main() {
    int nums[5] = { 1, 2, 3, 4, 5 };
    int** ans = permute(nums, 5);
    for (int i = 0; i < 120; i++)
        printf("%d %d %d %d %d\n", ans[i][0], ans[i][1], ans[i][2], ans[i][3], ans[i][4]);
    system("pause");
    return 0;
}