力扣------全排列_c语言全排列力扣

/**
 * Return an array of arrays of size *returnSize.
 * The sizes of the arrays are returned as *returnColumnSizes array.
 * Note: Both returned array and *columnSizes array must be malloced, assume caller calls free().
 */
int **ar;
int v;
void backtracking(int* nums,int b,int numsSize){
    if(b==numsSize){
        for(int j=0;j<numsSize;j++){
            ar[v][j]=nums[j];
        }
        v++;
        return;
    }
    else{
        for(int i=b;i<numsSize;i++){
            int a=nums[i];
            nums[i]=nums[b];
            nums[b]=a;
            backtracking(nums,b+1,numsSize);
             a=nums[i];
            nums[i]=nums[b];
            nums[b]=a;
        }
    }
}
int** permute(int* nums, int numsSize, int* returnSize, int** returnColumnSizes){
    int a=1;
    v=0;
    for(int b=1;b<=numsSize;b++){
        a=a*b;
    }
    *returnSize=a;
    
     (*returnColumnSizes) = (int*)malloc(sizeof(int) * (*returnSize));
   for (int i = 0; i < (*returnSize); i++) {
        (*returnColumnSizes)[i] = numsSize;
    }
    ar = (int**)malloc(sizeof(int*) * (*returnSize)); 
    for (int i = 0;i <(*returnSize);i++)
    {
        ar[i] = (int*)malloc(sizeof(int) * numsSize);
    }
    backtracking(nums,0,numsSize);
    return ar;
}
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