字符串_字符流中第一个不重复的字符|算法专题

    let container = new Array(256).fill(-1);
    let index = 0;
    function Init() {
      container = new Array(256).fill(-1);
      index = 0;
    }
    function Insert(ch) {
      const code = ch.charCodeAt(0);
      if (container[code] === -1) {
        container[code] = index;
      } else if (container[code] >= 0) {
        container[code] = -2;
      }
      index++;
    }
    function FirstAppearingOnce() {
      let minIndex = 256;
      let strIndex = 0;
      for (let i = 0; i < 256; i++) {
        if (container[i] >= 0 && container[i] < minIndex) {
          minIndex = container[i];
          strIndex = i;
        }
      }
      return minIndex === 256 ? '#' : String.fromCharCode(strIndex);
    }