97. Interleaving String（js）

97. Interleaving String

Given s1, s2, s3, find whether s3 is formed by the interleaving of s1 and s2.

Example 1:

Input: s1 = "aabcc", s2 = "dbbca", s3 = "aadbbcbcac"
Output: true

Example 2:

Input: s1 = "aabcc", s2 = "dbbca", s3 = "aadbbbaccc"
Output: false
题意：s3是否与s1和s2字符相交错相等
代码如下：

/**
 * @param {string} s1
 * @param {string} s2
 * @param {string} s3
 * @return {boolean}
 */
var isInterleave = function(s1, s2, s3) {
    if(s3.length!==s1.length+s2.length){
        return false;
    }
    var res=[];
    for(var i=0;i<s1.length+1;i++){
        res[i]=new Array();
        for(var j=0;j<s2.length+1;j++){
            res[i][j]=false;
        }
    }
    
    for(var i=0;i<s1.length+1;i++){
        for(var j=0;j<s2.length+1;j++){
            if(i===0 && j===0){
                res[i][j]=true;
            }else if(i===0){
                res[i][j]=(res[i][j-1] && s2[j-1]===s3[i+j-1])
            }else if(j===0){
                res[i][j]=(res[i-1][j] && s1[i-1]===s3[i+j-1])
            }else{
                res[i][j]=(res[i-1][j] && s1[i-1]===s3[i+j-1]) || (res[i][j-1] && s2[j-1]===s3[i+j-1])
            }
        }
    }
    return res[s1.length][s2.length]
};