【LeetCode】45. Jump Game II

• Difficulty: Hard

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.)

Note:
You can assume that you can always reach the last index.

分析

贪心法，时间复杂度O（n）

class Solution {public:int jump(const vector<int>& nums) {int step = 0; int left = 0;int right = 0;if (nums.size() == 1) return 0;while (left <= right) {++step;const int old_right = right;for (int i = left; i <= old_right; ++i) {int new_right = i + nums[i];if (new_right >= nums.size() - 1) return step;if (new_right > right) right = new_right;}left = old_right + 1;}return 0;}};