找出k个数相加得n的所有组合

Find all possible combinations of k positive numbers that add up to a number n,each combination should be a unique set of numbers.

 /**
  * Return an array of arrays of size *returnSize.
  * The sizes of the arrays are returned as *columnSizes array.
  * Note: Both returned array and *columnSizes array must be malloced, assume caller calls free().
  */
 #define SIZE 600
 int** function(int k, int n, int** columnSizes, int* returnSize) {
     int **ret=(int**)malloc(sizeof(int*)*SIZE);
     int *sum=(int*)calloc(SIZE,sizeof(int));
     int *countArray=(int*)calloc(SIZE,sizeof(int));
     int temp_n=n;
     int count=;
     int temp=;
     int temp_k=;
     int back=;
     *returnSize=;
     if(k==){
         *returnSize=;
         columnSizes[]=(int*)malloc(sizeof(int));
         columnSizes[][]=;
         ret[]=(int*)malloc(sizeof(int));
         ret[][]=n;
         return ret;
     }
     for(int i=;i<SIZE;i++){
         ret[i]=(int*)calloc(k,sizeof(int));
     }
     while(temp*k+(k-)*k/<=n){
         ret[(*returnSize)][]=temp;
         countArray[(*returnSize)]++;
        sum[(*returnSize)]=temp;
         temp++;
         (*returnSize)++;
     }
     while(ret[count][]!=){
         temp=ret[count][countArray[count]-]+;
         temp_k=k-countArray[count];
         while(temp*temp_k+(temp_k-)*temp_k/<=(n- sum[count])){
             if(temp_k==){
                 ret[count][countArray[count]]=n- sum[count];
                 break;
             }
             ret[count][countArray[count]]=temp;
             back=sum[count];
             sum[count]=sum[count]+temp;
             countArray[count]++;
             temp++;
             while(temp*temp_k+(temp_k-)*temp_k/<=(n- sum[count])){
                 for(int i=;i<countArray[count]-;i++){
                     ret[(*returnSize)][i]=ret[count][i];
                 }
                 ret[(*returnSize)][countArray[count]-]=temp;
                 countArray[(*returnSize)]=countArray[count];
                 sum[(*returnSize)]=back+temp;
                 temp++;
                 (*returnSize)++;
             }
             temp=ret[count][countArray[count]-]+;
             temp_k=k-countArray[count];
         }
         count++;
     }
     columnSizes[]=(int*)malloc(sizeof(int)*(*returnSize));
     for(int i=;i<(*returnSize);i++){
         columnSizes[][i]=k;
     }
     return ret;
 }