139 word break

139. 单词拆分

go：

func wordBreak(s string, wordDict []string) bool {
    n := len(s)
    dp := make([]bool, n + 1)
    dp[0] = true

    for i := 1; i <= n; i++ {
        for _, w := range wordDict {
            lw := len(w)
            if i >= lw && dp[i - lw] && s[i - lw : i] == w {
                dp[i] = true
            }
        }
    }

    return dp[n]
}