Word Break

中等 单词切分查看运行结果 

11%

通过

给出一个字符串s和一个词典，判断字符串s是否可以被空格切分成一个或多个出现在字典中的单词。

您在真实的面试中是否遇到过这个题？ 

Yes

样例

给出

s = "lintcode"

dict = ["lint","code"]

返回 true 因为"lintcode"可以被空格切分成"lint code"

标签 Expand 

字符串处理 动态规划

public class Solution {    /**     * @param s: A string s     * @param dict: A dictionary of words dict     */    public boolean wordSegmentation(String s, Set<String> dict) {       if (s == null || s.length() == 0) {            return true;        }        //找到dict 中最长单词的长度        int maxLength = getMaxLength(dict);        //        boolean[] canSegment = new boolean[s.length() + 1];                //最开始设为true, 符合s.length()==0的情况        canSegment[0] = true;        //遍历s里的每个单词        for (int i = 1; i <= s.length(); i++) {            canSegment[i] = false;            //            for (int j = 1; j <= maxLength && j <= i; j++) {                //canSegement[i-j] == false， continue ==> j+1, 开始下一轮循环                if (!canSegment[i - j]) {                    continue;                }                /**                 * substring(int beginIndex,int endIndex)                 * 返回一个新字符串，它是此字符串的一个子字符串。                 * 该子字符串从指定的 beginIndex 处开始，直到索引 endIndex - 1 处的字符。                 * 因此，该子字符串的长度为 endIndex-beginIndex。                 * "smiles".substring(1, 5) returns "mile"                 * beginIndex - 起始索引（包括）。                 * endIndex - 结束索引（不包括）。                 */                String word = s.substring(i - j, i);                //如果dict包含word,canSegment[i]设为true,break                if (dict.contains(word)) {                    canSegment[i] = true;                    break;                }            }        }        return canSegment[s.length()];    }        private int getMaxLength(Set<String> dict) {        int maxLength = 0;        for (String word : dict) {            maxLength = Math.max(maxLength, word.length());        }        return maxLength;    }}

/**         *    0 1 2 3 4 5 6 7          * s="l i n t c o d e" dict=["lint","code"]         * s.length = 8, maxlength = 4;         * i = 1,          *      canSegment[1] = false,         *      j = 1, canSegment[0] = true,s.substring(0,1) ==> "l" ==> if;         * i = 2,         *      canSegment[2] = false,         *      j = 1, canSegment[1] = false,continue;         *      j = 2, canSegment[0] = true,s.substring(0,2) ==> "li" ==> if;          * i = 3,         *      canSegment[3] = false,         *      j = 1, canSegment[2] = false,continue;         *      j = 2, canSegment[1] = false,continue;         *      j = 3, canSegment[0] = true,s.substring(0,3) ==> "lin" ==> if;          *i = 4,         *      canSegment[4] = false,         *      j = 1, canSegment[3] = false,continue;         *      j = 2, canSegment[2] = false,continue;         *      j = 3, canSegment[1] = false,continue;         *      j = 4, canSegment[0] = true, word = s.substring(0,4) ==>          *                    "lint" ==> if ==> canSegment[4] = true, break;         * i = 5,         *      canSegment[5] = false,         *      j = 1, canSegment[4] = true,s.substring(4,5) ==>"c" ==> if;         *      j = 2, canSegment[3] = false,continue;         *      j = 3, canSegment[2] = false,continue;         *      j = 4, canSegment[1] = false,continue;         *      j = 5, canSegment[0] = true,s.substring(0,5) ==>"lintc" ==> if;         *               * i = 6,         *      canSegment[6] =false,         *      j = 1, canSegment[5] = false,continue;         *      j = 2, canSegment[4] = true,s.substring(4,6) ==>"co" ==> if;         *      j = 3, canSegment[3] = false,continue;         *      j = 4, canSegment[2] = false,continue;         *      j = 5, canSegment[1] = false,continue;         *      j = 6, canSegment[0] = true,s.substring(0,6) ==>"lintco" ==> if;         *          * i = 7,         *      canSegment[7] =false,         *      j = 1, canSegment[6] = false,continue;         *      j = 2, canSegment[5] = false,continue;         *      j = 3, canSegment[4] = true,s.substring(4,7) ==>"cod" ==> if;         *      j = 4, canSegment[3] = false,continue;         *      j = 5, canSegment[2] = false,continue;         *      j = 6, canSegment[1] = false,continue;          *      j = 7, canSegment[0] = true,s.substring(0,7) ==>"lintcod" ==> if;          *          * i = 8,         *      canSegment[8] =false,         *      j = 1, canSegment[7] = false,continue;         *      j = 2, canSegment[6] = false,continue;         *      j = 3, canSegment[5] = false,continue;         *      j = 4, canSegment[4] = true,s.substring(4,8) ==>"code" ==> if         *                                  ==> canSegment[8] = true, break;         */

/**         *    0 1 2 3 4 5 6 7 8 9          * s="l i n t c o d e l i" dict=["lint","code"]         * s.length = 10, maxlength = 4;         * i = 1,          *      canSegment[1] = false,         *      j = 1, canSegment[0] = true,s.substring(0,1) ==> "l" ==> if;         * i = 2,         *      canSegment[2] = false,         *      j = 1, canSegment[1] = false,continue;         *      j = 2, canSegment[0] = true,s.substring(0,2) ==> "li" ==> if;          * i = 3,         *      canSegment[3] = false,         *      j = 1, canSegment[2] = false,continue;         *      j = 2, canSegment[1] = false,continue;         *      j = 3, canSegment[0] = true,s.substring(0,3) ==> "lin" ==> if;          *i = 4,         *      canSegment[4] = false,         *      j = 1, canSegment[3] = false,continue;         *      j = 2, canSegment[2] = false,continue;         *      j = 3, canSegment[1] = false,continue;         *      j = 4, canSegment[0] = true, word = s.substring(0,4) ==>          *                    "lint" ==> if ==> canSegment[4] = true, break;         * i = 5,         *      canSegment[5] = false,         *      j = 1, canSegment[4] = true,s.substring(4,5) ==>"c" ==> if;         *      j = 2, canSegment[3] = false,continue;         *      j = 3, canSegment[2] = false,continue;         *      j = 4, canSegment[1] = false,continue;         *      j = 5, canSegment[0] = true,s.substring(0,5) ==>"lintc" ==> if;         *               * i = 6,         *      canSegment[6] =false,         *      j = 1, canSegment[5] = false,continue;         *      j = 2, canSegment[4] = true,s.substring(4,6) ==>"co" ==> if;         *      j = 3, canSegment[3] = false,continue;         *      j = 4, canSegment[2] = false,continue;         *      j = 5, canSegment[1] = false,continue;         *      j = 6, canSegment[0] = true,s.substring(0,6) ==>"lintco" ==> if;         *          * i = 7,         *      canSegment[7] =false,         *      j = 1, canSegment[6] = false,continue;         *      j = 2, canSegment[5] = false,continue;         *      j = 3, canSegment[4] = true,s.substring(4,7) ==>"cod" ==> if;         *      j = 4, canSegment[3] = false,continue;         *      j = 5, canSegment[2] = false,continue;         *      j = 6, canSegment[1] = false,continue;          *      j = 7, canSegment[0] = true,s.substring(0,7) ==>"lintcod" ==> if;          *          * i = 8,         *      canSegment[8] =false,         *      j = 1, canSegment[7] = false,continue;         *      j = 2, canSegment[6] = false,continue;         *      j = 3, canSegment[5] = false,continue;         *      j = 4, canSegment[4] = true,s.substring(4,8) ==>"code" ==> if         *                                  ==> canSegment[8] = true, break;         * i = 9,         *      canSegment[9] =false,         *      j = 1, canSegment[8] = true,s.substring(8,9) ==>"l" ==> if;         *      j = 2, canSegment[7] = false,continue;         *      j = 3, canSegment[6] = false,continue;         *      j = 4, canSegment[5] = false,continue;         *      j = 5, canSegment[4] = true,s.substring(4,9) ==>"codel" ==> if;         *      j = 6, canSegment[3] = false,continue;         *      j = 7, canSegment[2] = false,continue;         *      j = 8, canSegment[1] = false,continue;         *      j = 9, canSegment[0] = true,s.substring(0,9) ==>"lintcodel" ==> if;         *         * i = 10,         *      canSegment[10] =false,         *      j = 1, canSegment[9] = false,continue;         *      j = 2, canSegment[8] = true,s.substring(8,10) ==>"li" ==> if;         *      j = 3, canSegment[7] = false,continue;         *      j = 4, canSegment[6] = false,continue;         *      j = 5, canSegment[5] = false,continue;         *      j = 6, canSegment[4] = true,s.substring(4,10) ==>"codeli" ==> if;         *      j = 7, canSegment[3] = false,continue;         *      j = 8, canSegment[2] = false,continue;         *      j = 9, canSegment[1] = false,continue;         *      j = 10, canSegment[0] = true,s.substring(0,10) ==>"lintcodeli" ==> if;         *                                           */