【位运算】从一万个数中找到刚拿掉的数

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采用异或技巧。

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#include <stdio.h>int xor_1(int* x, int n){int r = 0, i;for (i=0; i<n; ++i){r ^= x[i]; }return r;}int main(){int a[] = {1,2,3,4,5,6,7};int b[] = {1,2,3,4,5,7};printf("the diff of a and b is %d\n", \xor_1(a, sizeof(a)/sizeof(int)) ^ xor_1(b, sizeof(b)/sizeof(int)));return 0;}