codeforce 401C 构造

#include <iostream>#include <cstdio>using namespace std;int n, m;int main(int argc, char const *argv[]){while (~scanf("%d%d", &n, &m)){if (m < n - 1 || m > 2 * n + 2) printf("-1");else if (n >= m){for (int i = 0; i < m; i++) printf("01");for (int i = 0; i < n - m; i++) printf("0");}else if (2 * n >= m){for (int i = 0; i < m - n; i++) printf("110");for (int i = 0; i < 2 * n - m; i++) printf("10");}else{for (int i = 0; i < n; i++) printf("110");for (int i = 0; i < m - 2 * n; ++i) printf("1");}printf("\n");}return 0;}

n个0，m个1，构造一个序列，不能出现“00”或者“111”。

举例分析，注意无解的情况。