Javascript using charCode and .slice
\nvar modifyString = function(s) {\n    for(let i = 0; i < s.length; i++){\n        if(s[i] === \'?\'){\n            let charCode = 97\n            const charCo
```\nvar modifyString = function(s) {\n    for(let i = 0; i < s.length; i++){\n        if(s[i] === \'?\'){\n            let charCode = 97\n            const charCodeLeft = s.charCodeAt(i-1)\n            const charCodeRight = s.charCodeAt(i+1)\n            while(charCodeLeft === charCode || charCodeRight === charCode){\n                charCode++\n            }\n           s = s.slice(0,i) + String.fromCharCode(charCode) + s.slice(i+1)\n        } \n    }\n    return s\n};\n```
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