leetcode — jump-game-ii

/**
* // Source : https://oj.leetcode.com/problems/jump-game-ii/ *
* Created by lverpeng on 2017/7/17.
*
* 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.
*
* Your goal is to reach the last index in the minimum number of jumps.
*
* For example:
* Given array A = [2,3,1,1,4]
*
* The minimum number of jumps to reach the last index is 2.
* (Jump 1 step from index 0 to 1, then 3 steps to the last index.)
*
*/
public class JumpGame2 {

/**
* 找到需要跳的次数最少的方法
*
* 贪心算法：保证当前是是最优的，以期结果是最优的
*
* 先保证能调到最后的最好的解，然后再计算能跳到当前最好解位置的最好解
*
* @param arr
* @return
*/
public int jump (int[] arr) {
int end = arr.length - 1;
int count = 0;
while (end > 0) {
for (int i = 0; i < end; i++) {
if (i + arr[i] >= end) {
count ++;
end = i;
break;
}
}
}
return count;
}

public static void main(String[] args) {
JumpGame2 jumpGame2 = new JumpGame2();
int[] arr = new int[]{2,3,1,1,4};
System.out.println("2----->" + jumpGame2.jump(arr));
}
}