LeetCode OJ

原地归并。

下面是AC代码：

 public void merge(int A[], int m, int B[], int n) {
        
         int len = A.length;
         //first copy m elements of A to the end of A
         for(int i=m-1,j = len-1;i>=0;i--){
             A[j--] = A[i];
         }
         //merge the A and B
         int startA = len - m;
         int startB = 0;
         int i = 0;
         while(startA<len || startB<n){
             while(startA<len&& startB<n && A[startA]<=B[startB])
             {
                 A[i++] = A[startA];
                 startA++;
             }
             while(startA<len && startB<n && B[startB]<A[startA]){
                 A[i++] = B[startB];
                 startB++;
             }
             while(startA == len && startB<n){
                 A[i++] = B[startB++];
             }
             while(startB == n  && startA<len){
                 A[i++] = A[startA++];
             }
         }
     }

/**
      * second method very nice . from the end to start
      * @param A
      * @param m
      * @param B
      * @param n
      */
     public void merge2(int A[], int m, int B[], int n){
         int i = m+n-1;
         while(i>=0 &&( n>=0 || m>=0)){
             A[i--] = m-1 < 0? B[(n--)-1]:
                 n-1 < 0? A[(m--)-1] : A[m-1]>=B[n-1]? A[(m--)-1]:B[(n--)-1];
         }
     }