0030. Substring With Concatenation of All Words

# 30. Substring with Concatenation of All Words#

## 题目 #

You are given a string, s, and a list of words, words, that are all of the same length. Find all starting indices of substring(s) in s that is a concatenation of each word in words exactly once and without any intervening characters.

Example 1:

``````
Input:
s = "barfoothefoobarman",
words = ["foo","bar"]
Output: [0,9]
Explanation: Substrings starting at index 0 and 9 are "barfoor" and "foobar" respectively.
The output order does not matter, returning [9,0] is fine too.

``````

Example 2:

``````
Input:
s = "wordgoodgoodgoodbestword",
words = ["word","good","best","word"]
Output: []

``````

## 代码 #

``````
package leetcode

func findSubstring(s string, words []string) []int {
if len(words) == 0 {
return []int{}
}
res := []int{}
counter := map[string]int{}
for _, w := range words {
counter[w]++
}
length, totalLen, tmpCounter := len(words[0]), len(words[0])*len(words), copyMap(counter)
for i, start := 0, 0; i < len(s)-length+1 && start < len(s)-length+1; i++ {
//fmt.Printf("sub = %v i = %v lenght = %v start = %v tmpCounter = %v totalLen = %v\n", s[i:i+length], i, length, start, tmpCounter, totalLen)
if tmpCounter[s[i:i+length]] > 0 {
tmpCounter[s[i:i+length]]--
//fmt.Printf("******sub = %v i = %v lenght = %v start = %v tmpCounter = %v totalLen = %v\n", s[i:i+length], i, length, start, tmpCounter, totalLen)
if checkWords(tmpCounter) && (i+length-start == totalLen) {
res = append(res, start)
continue
}
i = i + length - 1
} else {
start++
i = start - 1
tmpCounter = copyMap(counter)
}
}
return res
}

func checkWords(s map[string]int) bool {
flag := true
for _, v := range s {
if v > 0 {
flag = false
break
}
}
return flag
}

func copyMap(s map[string]int) map[string]int {
c := map[string]int{}
for k, v := range s {
c[k] = v
}
return c
}

``````

Sep 6, 2020