基於KMP演算法JavaScript的實作方法分析_基礎知識

演算法的核心是部分匹配表和回退演算法，部分匹配表的實作如下：

複製程式碼 程式碼如下:

function kmpGetStrPartMatchValue(str) {
    var prefix = [];
    var c =0,j=str.length;i        var newStr = str.substring(0,i 1);
     partMatch[ i] = 0;
        } else {
            for(var k=0;k                suffix [k] = newStr.slice(-k-1);
                if(prefix[k]== suffix   ] = prefix[k].length;
                }
            }
           if(!partMatch[i]){        }
    }
    prefix.length = 0
;
    prefix.length = 0
;
;
; suffix.length = 0;
    return partMatch;
}

//demo
var t="ABCDABD";console.log(kmpGetStrPartMatchValue(t));

//output:[0,0,0,0,1,2,0 ]


回退演算法實作如下：

複製程式碼 程式碼如下: >function KMP(sourceStr,targetStr){    var partMatchValue = kmpGetStrPartMatchValue(targetStr);

    var result = false;

fmmo; ;i ){
        for(var m=0,n=targetStr.length;m          >                if(m == targetStr.length-1){
                      break;
                } else {            } else {
      (m>0 && partMatchValue[m-1] > 0){
                    m = partMatch }🎜>                    break;
           >        }
        if(result){
            result;
}
var s = "BBC ABCDAB ABCDABCDABDE";
var t = "ABCDABD";
console.log(KMP(s,t));
//output: true