[LeetCode] [Jump Game 2012-03-24]

Given an array of non-negative integers, you are initially positioned at the first index of the array.

Each element in the array represents your maximum jump length at that position.

Determine if you are able to reach the last index.

For example: A =

[2,3,1,1,4]

, return

true

.

A =

[3,2,1,0,4]

, return

false

.

class Solution {
public:

bool* isAccess;
bool* isComputed; //here is the key. like a memorandum, note, should not use isAccess, since "false" item might be computed several times
bool canReachRecursive(int A[], int m)
{
if(m == 0)  return true;
if(isComputed[m]) return isAccess[m];

for(int j=0;j<m;j++)
{
if(A[j] >= m-j && canReachRecursive(A, j))
{
isComputed[m]=true;
isAccess[m] = true;
return true;
}
}
isComputed[m]=true;
isAccess[m] = false;
return false;
}
bool canJump(int A[], int n)
{
isAccess = new bool
;
isComputed = new bool
;
for(int i=0;i<n;i++)
{
isAccess[i]=false;
isComputed[i] = false;
}
return canReachRecursive(A, n-1);
}
};