LeetCode 514: Freedom Tail

weixin_33768481

于 2017-10-11 14:56:00 发布

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原文链接：http://www.cnblogs.com/shuashuashua/p/7650567.html

本文介绍了一种求解在旋转圆环形键盘上输入特定字符串所需的最小步数的算法。通过动态规划的方法，考虑了从任意位置开始到目标字符所需的最短距离，并实现了高效的计算。

Note:

DP means we have (i, end) keys and starting from j position how many "STEPS" we need. This does not include press button step.

class Solution {
    public int findRotateSteps(String ring, String key) {
        int[][] dp = new int[key.length() + 1][ring.length()];
        for (int i = key.length() - 1; i >= 0; i--) {
            for (int j = 0; j < ring.length(); j++) {
                dp[i][j] = Integer.MAX_VALUE;
                for (int k = 0; k < ring.length(); k++) {
                    if (key.charAt(i) == ring.charAt(k)) {
                        int diff = Math.abs(j - k);
                        int step = Math.min(diff, ring.length() - diff);
                        dp[i][j] = Math.min(dp[i][j], dp[i + 1][k] + step);
                    }
                }
            }
        }
        return dp[0][0] + key.length();
    }
}