原地归并。
下面是AC代码：
1 public void merge(int A[], int m, int B[], int n) { 2 3 int len = A.length; 4 //first copy m elements of A to the end of A 5 for(int i=m-1,j = len-1;i>=0;i--){ 6 A[j--] = A[i]; 7 } 8 //merge the A and B 9 int startA = len - m; 10 int startB = 0; 11 int i = 0; 12 while(startA<len || startB<n){ 13 while(startA<len&& startB<n && A[startA]<=B[startB]) 14 { 15 A[i++] = A[startA]; 16 startA++; 17 } 18 while(startA<len && startB<n && B[startB]<A[startA]){ 19 A[i++] = B[startB]; 20 startB++; 21 } 22 while(startA == len && startB<n){ 23 A[i++] = B[startB++]; 24 } 25 while(startB == n && startA<len){ 26 A[i++] = A[startA++]; 27 } 28 } 29 }
1 /** 2 * second method very nice . from the end to start 3 * @param A 4 * @param m 5 * @param B 6 * @param n 7 */ 8 public void merge2(int A[], int m, int B[], int n){ 9 int i = m+n-1; 10 while(i>=0 &&( n>=0 || m>=0)){ 11 A[i--] = m-1 < 0? B[(n--)-1]: 12 n-1 < 0? A[(m--)-1] : A[m-1]>=B[n-1]? A[(m--)-1]:B[(n--)-1]; 13 } 14 }