Smallest Difference(POJ-2718)

標籤：acm   poj   

暴搜一下就行了，確實也沒法最佳化什麼。 不過枚舉一半，另一半用next_permutation()函數應該是會快一些的。

#include<cstdio>#include<cstring>#include<iostream>#include<algorithm>#include<queue>#include<cmath>using namespace std;int T,a[20],n,vis[20],tot;int A[20],B;void dfs(int cur) {    if(cur==n/2) {        int b[20],kase = 0;        for(int i=0;i<n;i++) {            if(!vis[i]) b[kase++] = a[i];        }        sort(b,b+kase);        do {            int t=0;            if(b[0]==0&&n-cur>1) continue;            for(int i=0;i<kase;i++)                t = t*10 + b[i];            int c = abs(t-B);            if(c<tot) tot = c;        } while(next_permutation(b,b+kase));    }    else for(int i=0;i<n;i++) {        if(cur==0&&a[i]==0) continue;        if(!vis[i]) {            B=B*10+a[i];            A[cur] = a[i];            vis[i] = 1;            dfs(cur+1);            B = (B-a[i])/10;            vis[i] = 0;        }    }}int main() {    scanf("%d",&T);    char c = getchar();    while(T--) {        char s[100];        int kase = 0;        gets(s);        n = strlen(s);        for(int i=0;i<n;i++) {            if(s[i]!=' ') {                a[kase++] = s[i]-'0';            }        }        n = kase;        memset(vis,0,sizeof(vis));        memset(A,0,sizeof(A));        B = 0;        tot = 1000000000;        dfs(0);        printf("%d\n",tot);    }    return 0;}

Smallest Difference(POJ-2718)