一.
public intfindLast(int[] x, inty) {
//Effects: If x==null throw
NullPointerException
// else return the index of the last element
// in x that equals y.
// If no such element exists, return -1
for (inti=x.length-1; i> 0; i--)
{
if (x[i] == y)
{
return i;
}
}
return -1;
}
// test: x=[2, 3, 5]; y = 2
// Expected = 0
1. i>0 改为 i>=0
2.x=[3,4,5];y=5
3.x=[3,4,5];y=6
4.x=[3,4,5];y=3
public static intlastZero(int[] x) {
//Effects: if x==null throw
NullPointerException
// else return the index of the LAST 0 in x.
// Return -1 if 0 does not occur in x
for (inti= 0; i< x.length; i++)
{
if (x[i] == 0)
{
return i;
}
} return -1;
}
// test: x=[0, 1, 0]
// Expected = 2
1.for (inti= 0; i< x.length; i++) 改为 for (int i=x.length-1; i>= 0; i--)
2.x=[0,4,5];y=0
3.x=[0];y=0
4.x=[0];y=0