function f(s){ let stack = []; const map = new Map([['}', '{'],[']', '['], [')', '(']]); const map2 = new Map([[ '{','}'],['[',']' ], [ '(',')']]); for(let i = 0; i < s.length; i++){ if(s[i] === '[' || s[i] === '(' || s[i] === '{'){ stack.push(i); }else{ if(stack.lenght === 0){ console.log(i, map.get(s[i])); return; }else if(map.get(s[i]) === s[stack[stack.length-1]]){ stack.pop(); }else{ if(stack.length < 2){ console.log(i, map.get(s[i])); return; }else{ if(map.get(s[i]) === s[stack[stack.length-2]]){ console.log(i,map2.get(s[stack[stack.length-1]])); return; } } } } } } 不知道对不对