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Commit 8cae1cb

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add: Decode Ways
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‎README.md‎

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@@ -31,6 +31,7 @@ This is the solutions collection of my LeetCode submissions, most of them are pr
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|69|[Sqrt(x)](https://leetcode.com/problems/sqrtx/) | [JavaScript](./src/sqrtx/res.js)|Easy|
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|73|[Set Matrix Zeroes](https://leetcode.com/problems/set-matrix-zeroes/) | [JavaScript](./src/set-matrix-zeroes/res.js)|Medium|
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|75|[Sort Colors](https://leetcode.com/problems/sort-colors/) | [JavaScript](./src/sort-colors/res.js)|Medium|
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|91|[Decode Ways](https://leetcode.com/problems/decode-ways/) | [JavaScript](./src/decode-ways/res.js)|Medium|
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|130|[Surrounded Regions](https://leetcode.com/problems/surrounded-regions/) | [JavaScript](./src/surrounded-regions/res.js)|Medium|
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|136|[Single Number](https://leetcode.com/problems/single-number/) | [JavaScript](./src/single-number/res.js)|Easy|
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|175|[Combine Two Tables](https://leetcode.com/problems/combine-two-tables/)| [SQL](./src/combine-two-tables/res.txt)|Easy|

‎src/decode-ways/res.js‎

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/**
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* res.js
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* @authors Joe Jiang (hijiangtao@gmail.com)
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* @date 2017年04月06日 18:43:29
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*
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* A message containing letters from A-Z is being encoded to numbers using the following mapping:
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* 'A' -> 1
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* 'B' -> 2
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* ...
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* 'Z' -> 26
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*
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* Given an encoded message containing digits, determine the total number of ways to decode it.
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*
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* For example,
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* Given encoded message "12", it could be decoded as "AB" (1 2) or "L" (12).
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*
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* The number of ways decoding "12" is 2.
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*
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* @param {string} s
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* @return {number}
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*/
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let numDecodings = function(s) {
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let len = s.length,
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num = 0,
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matrix = new Array(len);
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if (len===0) return len;
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for (let i=0; i<len; i++) {
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matrix[i] = new Array(len);
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if (s[i] !== '0') {
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matrix[i][i] = 1;
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} else {
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matrix[i][i] = 0;
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}
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}
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let i=0;
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for (let j=1; j<len; j++) {
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let subOne = 0,
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subTwo = 0,
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subTwoStr = Number.parseInt(s.substring(j-1, j+1));
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if (s[j] !== '0') {
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subOne = matrix[i][j-1];
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}
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if (subTwoStr > 9 && subTwoStr < 27) {
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subTwo = j-i === 1? 1:matrix[i][j-2];
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}
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if (subOne === 0 && subTwo === 0) return 0;
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matrix[i][j] = subOne + subTwo;
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console.log(matrix[i][j]);
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}
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return matrix[0][len-1];
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};

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