LeetCode:Jump Game

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

.

两种思路，从前往后和从后往前，看能够到达的最远的点。

实现代码：

class Solution {
public:
bool canJump(int A[], int n) {
int reach=0;
int i=0;
for(;i<n&&i<=reach;i++)
{
reach=max(i+A[i],reach);
}
return i==n;
}
};

或者从后往前推：

class Solution {
public:
bool canJump(int A[], int n) {
int last=n-1,i,j;
for(i=n-2;i>=0;i--)
{
if(A[i]+i>=last)
last=i;
}
return last<=0;
}
};