[рони]

misha.korolcov,

const arrOne = [{
                city: '111',
                price: 1
            },
            {
                city: '222',
                price: 2
            },
        ]
        const arrTwo = [{
                city: '111',
                price: 0
            },
            {
                city: '333',
                price: 0
            },
            {
                city: '444',
                price: 0
            },
        ]

        const res = (...arr) => {
            const obj = {};
            return arr.flat().filter(ob => {
                let {
                    city,
                    price
                } = ob;
                if (obj[city]) {
                    obj[city].price += price;
                    return false
                } else {
                    obj[city] = ob
                };
                return true
            })
        }

        console.log('res', res(arrOne, arrTwo))