问题
My problem is to add the sum of each row in a 2d array, and put those values in a new 1d array.
This is my code
public static int[] sumRow(int[][] N){
int[] rowSum = new int[N.length];
for(int i = 0; i<N.length;i++){
for(int j = 0; j<N[i].length; j++){
rowSum[i] = N[i][j] + N[i+1][j+1];
}
}
return rowSum;
}
But it is not working, please help.
回答1:
public static int[] sumRow(int[][] N){
int[] rowSum = new int[N.length];
for(int i = 0; i<N.length;i++){
rowSum[i] = 0; //<= initialize value
for(int j = 0; j<N[i].length; j++){
rowSum[i] += N[i][j]; //<= sum of row
}
}
return rowSum;
}
You have written most of the code right but you need to add each row so, you need to add N[0][1], ....N[0][N[0].length - 1] in row 0. Now just plug i and j values and write on paper to be much clear.
回答2:
Try this.
public static int[] sumRow(int[][] N) {
return Stream.of(N)
.mapToInt(a -> IntStream.of(a).sum())
.toArray();
}
来源：https://stackoverflow.com/questions/35905584/java-how-to-add-sum-of-a-row-in-2d-array