func searchMatrix(matrix [][]int, target int) bool {
if len(matrix) == 0 {
return false
}
col,row := 0,len(matrix[0])-1
for col < len(matrix) && row >= 0 {
t := matrix[col][row]
if target == t{
return true
}else if target < t {
row --
}else {
col ++
}
}
return false
}