```
public boolean searchMatrix(int[][] matrix, int target) {
int line=0;
int len=matrix.length;
int col=matrix[0].length;
while (line<len && col>0){
int num= matrix[line][col-1];
if (num>target) col--;
if (num<target) line++;
if (num==target) return true;}
return false;
}
```

The main idea of this solution is to compare the target with the number in the top-right corner and decrease the row number or the col number one by one. It's simple and efficient.