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export default function kSimilarity(s1: string, s2: string): number {    let str1 = "";    let str2 = "";    for (let i = 0; i < s1.length; i++) {        if (s1[i] !== s2[i]) {            str1 += s1[i];            str2 += s2[i];        }    }    if (str1.length === 0) {        return 0;    }    let ans = str1.length - 1;
    function dfs(        pos: number,        cost: number,        len: number,        str1: string | string[],        str2: string,    ) {        if (cost > ans) {            return;        }        while (pos < str1.length && str1[pos] === str2[pos]) {            pos++;        }        if (pos === str1.length) {            ans = Math.min(ans, cost);            return;        }        /* 当前状态的交换次数下限大于等于当前的最小交换次数 */        if (cost + minSwap(str1, str2, pos) >= ans) {            return;        }        for (let i = pos + 1; i < str1.length; i++) {            if (str1[i] === str2[pos]) {                const str1Next = swap(str1, i, pos);                dfs(pos + 1, cost + 1, len, str1Next, str2);            }        }    }
    dfs(0, 0, str1.length, str1, str2);    return ans;}function minSwap(s1: string | string[], s2: string | string[], pos: number) {    let tot = 0;    for (let i = pos; i < s1.length; i++) {        tot += s1[i] !== s2[i] ? 1 : 0;    }    return Math.floor((tot + 1) / 2);}
function swap(cur: string | string[], i: number, j: number) {    const arr = [...cur];    const c = arr[i];    arr[i] = arr[j];    arr[j] = c;    return arr;}